“It said they don’t use GPS and don’t track your location. Then how would they know if I’ve been close to somebody else who they also don’t track?”
Bluetooth.
Bluetooth has a range of 30 feet, sometimes more. If they don’t record your location, the warning is going to be “you were within 30 feet of an infected person for X minutes today”
Is that the slightest bit useful to anybody?
The info said they are using signal strength to infer proximity.
“It said they don’t use GPS and don’t track your location. Then how would they know if I’ve been close to somebody else who they also don’t track?”
Bluetooth.
Bingo. Turn it off.
Bluetooth.
My sister told of a visit to Starbucks a few years back, standing in line behind a stranger, they exchanged a few pleasantries while waiting for the coffee, then they each went their way.
Later that day she saw a FB recommendation for "people you may know" and it showed the picture of that stranger from Starbucks.
I think our phones are also listening to us, even if we have disabled Snoopy Siri (if that's even possible). Stuff shows up on her phone and mine (since we are frequently together) that flat-out creeps us both out.
I've been carrying my iParasite in a Faraday bag ever since, and disabled all the busy-body tracker doodads I can find, especially now that this Covid Craziness has infected peoples minds, as if the very air we breathe is poisoned with a covid gas or something. I really hate this gadget. I remember party-line phones that hung on the wall, and you had to be home to know if someone called; now people seem to be unable to function without their privacy intrusion device in hand.