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Comment by nabusman | Hacker News Reader

Grocery stores do not just use the data internally but also sell their Point of Sale data to third parties that analyze it and then sell their analysis to anyone willing to pay for it (mostly that is CPG companies). Point is: it isn't necessarily a direct benefit to the end customer.

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I have never looked this up, but anytime I'm checking out at a brick and mortar store, I'm asked, casually, "Phone number?" Or "Zip code?" As if thats information that is necessary to check out. My response is always, politely, "you don't need that information." It annoys my wife because she thinks I'm being rude, but frankly the question I'm being asked is uncouth. Would you ask a stranger how many children they have or what time they get off work? Not unless you had some intention to use that information!

Just poison the data.

Phone number? 212 555 1212. (You could change to the local area code if you feel like it.)

ZIP code? 90210, in Beverly Hills, of course. Or 01234, which is Pittsfield, Massachusetts.

The problem is that this info is tied to warranty information sometimes.

for expensive purchases maybe that's important

for my weekly purchase of bread, bacon and ketchup it's definitely not

I don't know what I'd do without the feeling of security I get from my comprehensive ketchup warranty.

I had a massive ketchup blow-out recently. It took out my entire refrigerator. There was leftover lasagna and broken beer bottles everywhere.

I'm just glad I'd bought the extended warranty.

Agreed.

Local area code plus Jenny's number has worked everywhere I've ever tried

Smart. Years ago I registered the number 500-5000 everywhere I could in my neighborhood. Just from word of mouth, the number got so popular they banned it at the local grocery store!

Give the phone number and zip of the store asking for the information. This way if there is data leak it is theroretically possible to track who originally asked for the data. This self-reference trick can be done with email address as well. The idea is that, in the event of unwanted data sharing, the consumer needs some way to know where the personal data came from originally.

I actually requested a card at Safeway (wanted for convenience, not privacy), but apparently they are not giving those out anymore. You have to give them your phone number or else accept the additional costs for your food and lack of benefits at the gas station.

The rewards card is a much better model in my opinion because while it gives them quite a bit of data, it does provide some anonymity. I'm sure it is possible to reconstruct from that data who I am (i.e. convert it into direct PII like name and address), but that at least takes a lot more effort and processing than if they have my phone number.

Most people are ok giving up SOME privacy for the sake of convenience/cost savings. I doubt most people are truly willing to give up all privacy for said benefits once they understand what they are actually giving up.

Rewards cards offer zero anonymity. Their entire purpose is to keep track of your purchase activity so you can be profiled by data brokers.

Is there anything stopping you from getting a card for 555-867-5309?

They need a phone number. I've never heard of any store actually trying to use it to contact you.

PS: If you ask nicely the cashier will almost always punch in a working number for you. They want the reward points.

Not at most places and often times that number will have a large reward points pool already built up because others are also using it to avoid giving out their number.

The typical model that I'm familiar with on those rewards cards is that they just ask for that same info for you to get the card in the first place, so it's of basically no benefit privacy-wise. I suppose this can differ from place to place, and you could always supply a different number or one not strongly linked to you, I guess.

You use your reward card when paying with a credit card? Or have you only ever paid cash?

Because if you have, your reward card has probably already been linked to your credit card, phone number, email, etc. by now.

That at least takes extra processing and data sets. I think that does matter as far as privacy is concerned. We tend to think of privacy and security as all or nothing, but it really doesn't have to be that way and may be impossible to achieve if you go down that route.

How do tourists react to those questions, or how does your wife react to stores not asking such questions in other countries?

Just say "no thanks" and you get the same result while sounding less rude.

I hope you realize that grocery stores track you in other ways than just your zip code or phone number [1]. You have a beacon in your pocket that is always searching for SSIDs or Bluetooth IDs, which is more than enough to uniquely ID you. You can combine that with facial rec now and link a face, sex and estimated age to the SSID combo. Who names their phone “<Your name>’s iPhone”? They can get your name too.

If you truly wanted to be paranoid, set your device to airplane mode (don’t forget your smartwatch or wallet Tile), cover your face (this shouldn’t be hard these days) and only then venture into a store. Oh, and pay your groceries with cash.

[1] This article is from 8 years ago, so just imagine how far we came from that time: https://lifehacker.com/how-retail-stores-track-you-using-you...

> It annoys my wife because she thinks I'm being rude

You are being rude. The innocent cashier is forced to ask you that question and has no power to change the rules. Why not be polite to them? If you really want to change things, try asking to speak to the manager (after you're done checking out, of course!).

How is not giving personal information rude? He is just telling them the truth that they don't need that information which is correct. If a cashier were to ask you your bra size would you be okay with it? Why is it okay to ask for phone number which will give you all that and more.

politeness and truth are orthogonal concepts. You can be both right and rude. Watching the Big Bang Theory can provide a feel for this.

you can be both honest and polite.

Politeness is also relative to whom you are speaking to.

> You are being rude. The innocent cashier is forced to ask you that question and has no power to change the rules.

Then the person being rude is the person forcing the cashier to do this. The customer should push back, so the cashier can push back.

Both are rude.

The cashier and customer should both realize that neither of them want to do this, and be polite about it.

The cashier has to do that all day, every day though, so I feel like they get a pass.

If you push back, nothing happens to you.

If the cashier pushes back, they may be punished (up to and including getting fired — there's more competition for cashier-level jobs than you think).

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