More seriously, Street View as lint for road signs would be a superb idea! It's probably not something that anyone short of Google would have the processing power to do, but it would help a great deal.
(Assuming municipalities want help, that is. There are plenty of small towns that operate as speed traps, looking to shake down drivers by posting few speed-limit signs and many traffic cops. But lint-for-road-signs could reveal when an area has unresolved road-sign issues, and warn drivers to take another route.)
(Top HN post in Feb 2021: "Alphabet Corp announces it's dropping support for GoogleBlood starting April 1st: A blogpost advises users to replace their blood with blood from alternative vendors and restore from backups as access to all blood functionality (not just the SmartBlood(tm) features) will cease at midnight Mar 31th. Advertisers with prepaid in-blood advertising bids will be pro-rata credited in their AdsInside account.")
I don't really know why you'd think that line would be the one thing holding them back from super villainy, but you'll be relieved to know that it's definitely still there:
Arcing power lines can be tracked down with with a shortwave radio and reported, but the powerline adapters are a nightmare. They're suppposed to notch out the amateur radio bands but many do not, often swamping everything from 3 to 30MHz with noise.
In PLC (power-line communication), wiring is not meant to act as antenna. All transceivers are wired. It's an undesirable, unintentional side effect of limited (to the extent of complete lack of) cable shielding - because, well, power lines are usually meant for different application than data transfers.
Wouldn't ethernet cables have the same issues? Does the increased power flowing through power lines somehow amplify the signal? Is that pretty much the definition of what a power amplifier in a radio does, add juice to a signal on an antenna so it gets broadcast further?
Does the amount of wattage going through the line effect how "loud" the interference is?
Interestingly enough, there is enough radiation that you don't really need an actual connection. Someone put one of the endpoints in a field with a generator and got a connection to another endpoint. In a sense power line adapters are just using radio over the air.
Sending data over a power line, even at low bit rates is very difficult to do reliably. So all the radiation is in a sense a feature in that it improves connectivity. Not so much a feature to those who have an actual licence to use those frequencies...
That said, I think that these devices are actually quite rare in the real world - most people don't even seem to know what they are - and in my testing the noise dissipates very quickly as I leave my house, disappearing into the background of the city after only 20-30 feet.
I think that regulators have definitely dropped the ball on HomePlug, but I also don't think that it's that much of a problem, particularly given that it's been a commercial failure. Most of the ire towards HomePlug comes from people being upset about commercial-scale BPL installations, which actually have the potential to be a major problem over a large area.
In my house, my monitors actually account for more problems I experience than the HomePlug adapters do, in my everyday radio usage. And they aren't even cheap knockoffs, they're pricey name-brand models.
The refineries in the Houston area play all sorts of fast and loose with monitoring the chemicals they let go into the environment. If Google could measure stuff like this across wide geographical areas near the refineries, some good could come of this.
On the other hand, for all I know, the problem had been there for years.