Providers issue SIM (subscriber identity module) cards to uniquely authenticate subscribers to their network. Why do you need something that is constant across SIM cards? It's superfluous identifying information (GDPR wants a word!).
I believe network-IMEI-registration isn’t the primary mechanism by which modern phone anti-theft works by, though, since the device-owner is free to change the phone’s network-reported IMEI (much like you can change an Ethernet controller’s network-reported MAC address.) I might be wrong here, though; the phone’s baseband might come up with its burned-in IMEI and check for validity with the server, before switching to any application-processor-requested IMEI. (You can get around that by just booting up the phone in a Faraday cage—but having to do that every time would definitely decrease the black-market resale value.)
For iOS, at least, I think the anti-theft works by getting onto wi-fi each time the SIM changes and asking some activation server about the validity of [some other internal static device-ID that can’t be tampered with in this way]. Not so sure what, if anything, Android does (Android’s case is harder, since for phones with an unlocked bootloader, you can always flash an altered firmware that has no anti-theft logic.)
Also for most phones it's trivial to change the IMEI to resell the phone, or simply part it out. Which sure, are more things manufacturers see as bugs, to the frustration of legitimate activity - hence Right to Repair. The majority of the world is honest. Let's not build ourselves into a prison just to fallaciously protect against the few who aren't.
Errr, to be clear, the reason that phones don’t get stolen is that there are anti-theft measures in place.
People steal similar types of item (e.g. car stereos, game consoles, Blu-ray players) all the time. There’s no reason other than anti-theft measures that phones as a type of item would be stolen any less than these other categories. (They’d actually be stolen far more, since they’re small/easy to slip into one’s clothes/not a weird thing to be carrying around; and are often found just left on tables at cafes or hanging out of people’s back pockets. They’re like cash, basically.)
It’s the same reason that people steal bicycles more often than they steal cars. Bicycles, despite being worth much less, are just much easier to steal.
> The majority of the world is honest.
Do you live in a city? I’ve had my bicycle stolen five times now. I’ve also been mugged twice. I’ve never had my phone stolen, though—because it’s worthless to the sort of dumb criminals who steal things just to hawk them on the street, rather than to fence them.
It doesn’t require a large fraction of the world to be dishonest, to result in most people in the world having crimes committed against them. A thief will steal from far more than one person in their thieving career. Especially in regimes where the computed ROI for going after certain types of thief (e.g. homeless, drug-addicted thieves) is negative (i.e. their prison housing costs society more than their thieving does, apparently), and so they’re never held for more than a day or two.
Activation lock actually helps to reduce phone theft, but IMEI blacklisting is basically totally worthless. It's way too easy to change a phone's IMEI for it to be useful, and you often don't even have to do that, since just taking the phone to a foreign country is often enough to evade the blacklist.
Bikes are actually a great analogy. Even though bike thefts are a concern, I still wouldn't want any of my bikes to have a built in location tracking to discourage theft! I'd rather suffer the mitigations I mentioned above, and consider losing a beater bike as part of the cost of transportation, than have my movements permanently recorded.
Similarly, I did and still do have no problem carrying a few hundred dollars cash. In general, remaining an autonomous individual requires being in possession of things of value that you control. Relying on some overarching system to take care of them for you results in that system inherently controlling you.
Most thefts are committed by thieves who operate alone. (This is verifiable at least for my own country; I asked a crime-statistics analyst friend of mine.) Thus, most deterrence is focused on deterring the thieves who act alone.
This is the same reason that “security locks” aren’t actually proof against professional thieves. They’re not meant to deter thieving rings; they’re just meant to deter the thieves who are acting alone. Such thieves might have watched a tutorial or two on YouTube on lock-picking, and they might have picked up a lock-picking set from AliExpress; but they don’t have (and aren’t willing/able to invest in) the sort of lock-picking skills/tools that professionals have (e.g. slide-hammers, impact drivers, etc.) so an average security lock will be enough to stymie them.
Same with clubs on cars: no proof against professional thieving rings, but good enough to make a thief acting alone look elsewhere.
Just like there is a qualitative difference in how people treat things that are “free” vs. “$0.01”, there is a qualitative difference in theft rates between “no security” and “trivial security.” Most property crimes are spur-of-the-moment, committed by people who didn’t come prepared to steal something, but just see an opportunity to take something and feel the need to have it. Put a trivial barrier in the way of taking things, and those spur-of-the-moment crimes committed by “amateur thieves” go away.
In any case, maybe that is not so much the case in the US. But this certainly is the case in Europe; a very, very large percentage of stolen phones are sent to facilities that will part them out or unlock them.
It also is true that someone selling a locked phone on Kijiji is likely to end up selling it to someone who has the skill or who knows someone that can unlock it.
But again, that's post-hoc statistics. You're looking at the world that already has the trivial disincentive against amateur thieving. So of course you'll see most stolen phones being stolen by professionals—the amateur thieves are already not bothering, so if a phone is being stolen at this point, it's being stolen by a professional thief!
In a world without that disincentive, the statistics would skew very differently.
I again compare to the market for stolen bicycles. Yes, there are professional thieves with "bicycle chop shops" et al. But there are also crackheads carrying around bolt-cutters who just want to take a bike they walk by, ride it back to the ghetto, and then sell it for $20 to a street passerby to buy their next fix. Most cities have a large bike-theft problem, and it's mostly from this kind of thief, not from professional thieves. Any "security bike lock"—i.e. any bike lock you can't just snip through with bolt cutters—stops this kind of thief.
Look at New York City, for example. There are two types of bikes in NYC: those with security locks, and those that get stolen the instant they're left alone for ten minutes. The security lock wouldn't deter a professional thief—but a professional thief prioritizes, stealing fancy bikes from e.g. university sports department bike parkades, and won't bother with your average commuter bike. The crackhead does not prioritize. They just want $20, and your bike is probably worth $20.
The selection process for phones is already there: unless you are a very good thief, you're not stealing cellphones. That's because realistically your two ways of stealing a cellphone is either skillful pick-pocketing/misdirection, or muggings. Now if you're a crackhead, mugging people is not a very good idea for obvious reasons, and the subtler ways of stealing a cellphone already select for experienced thieves.
The number one reason why bikes are stolen so much is not because they are easy to steal, it is because there is essentially no risk of getting caught. No one will give a shit if you're stealing a bike, and so even professional bike thieves will simply pop your lock with a Ramset gun without a care in the world and be on their merry way hours before you even notice. Whereas stealing a cellphone, unless very skillful, requires direct confrontation, which is not an issue.
>But again, that's post-hoc statistics. You're looking at the world that already has the trivial disincentive against amateur thieving. So of course you'll see most stolen phones being stolen by professionals—the amateur thieves are already not bothering, so if a phone is being stolen at this point, it's being stolen by a professional thief!
I seriously disagree for the reasons I outlined above. The kind of people that would steal phones are the kind of people that know how to offload it. Again, maybe this is different in the US, but anyone with shady friends here could figure out how to fence a stolen phone. It's really not nearly as exclusive as you might think. I personally know two people I could offload a stolen phone (that I entered into contact via my elementary school of all places), and I am very, very, very far from being the kind of person that needs to steal phones in order to subsist. The hardest crime I ever did was to give my friend a USB key with mp3s of Akon in 2011.
And even if it wasn't the case, do you really think a crackhead would not try to steal a phone anyways? Of course they would, and they could probably figure out a way to fence it for 20$ or so. They just don't want to because stealing something that is either in your pocket or in your hands 24/7 is way too much risk for way too little reward.
The only thing IMEI blacklisting has succeeded in doing is making it a bitch to buy phones on the used market. At any time the seller could do insurance fraud and claim the phone is stolen and now that phone is (domestically) a tablet at best and the purchaser is left with no recourse. At least with a vendor system like iCloud, there's a fast way to make sure the phone's signed out when you do a purchase on Craiglist or other third party site.
At some point we're going to be looking at titling phones (I'm amazed Apple hasn't done so yet) if we ever want to see a used phone market without insurance requirements happen again.
Right now, if you buy a phone and it ends up on the blacklist after the return period, you can find a service that changes the IMEI or figure it out yourself if you can stand to wade through forum FUD. Since a significant number of blacklisted phones are from broken finance contracts, a phone simply being in the blacklist does not imply that it was stolen - a broken finance contract is a civil matter purely between the carrier and the original owner. Therefore, rewriting the IMEI on such a phone is completely legal, at least in the US.
Whereas if phones had titles, then a financed phone could have a legal encumbrance recorded on that title after you thought you'd bought it outright, and changing the IMEI to get out from that would be illegal. Phones are not incorporeal, immovable, expensive, or dangerous devices. Lacking all of the usual justifications for existing title systems, heading away from draconian registration makes more sense than heading towards it.
You will notice this happen - If your phone is stolen in Europe, it will almost invariably end up later in North Africa, then disappear entirely shortly after. Similar stories for stolen phones in NA, I'm sure.
As for iOS anti-theft, that also can be defeated in various ways.
In any case, anti-theft is not a proper justification for IMEIs being unique. Any anti-theft in a device that has been integrally stolen will be bypassed. These phones get fenced to people in third world countries with very very good reverse-engineering and electronics skills, and it only takes one to find out how to bypass any given issue. And worse comes to worst, they will sell the parts and still make a few hundred dollars out of your phone.