Uhhh that exact technology has been in use for years. Your phone broadcasts/receivers a beacon at regular intervals while Bluetooth is on. Anyone can pick it up if they are looking.
https://www.nytimes.com/interactive/2019/06/14/opinion/bluetooth-wireless-tracking-privacy.html
The process is so streamlined companies bragged your advertising profile is updated before you check out.
The Next Major Version of Bluetooth Might Help Advertisers Track Your Smartphone Faster
FIFY
Let’s not pretend this feature didn’t trickle down the data harvesting dog-hydrant to us peons solely for our benefit.
Ha! Yes! Even today USB 5 volts is pretty sweet for low power stuff. USB PD re-complicates things, but it’s not user dependent so that’s a plus.
And you need a loooot of copper to prevent voltage drop especially when a grid of 100 houses 1/2 mile long draw 20-80 amps each. The math starts adding up real quick.
I heard it said many years ago that if DC won the battle, we’d have power stations every 10 miles and power lines as thick as your wrist.
Converting local power is fairly easy, with AC inverters added for universal compatibility.
But, take note of how many DC voltages you use in your house. Devices in mine range from 3v to 25v and some weird one like 19v for a laptop. You’d still have adapters all over the place.
The user may not be aware they have this tracking technology on their phone. The toolkit may be some app developer integrating a 3rd party library for analytics. Banking apps, loyalty apps, phone companies, games, utilities… they all can rely on 3rd parties for proximity services.
In fact, I was going to mention an app, Exodus, that can reveal these trackers and in scanning my phone, I found 2!. The first is home assistant, which is understandable, but the second is a Health app my doctor office uses! Man, that irks me!