A few months ago I chose a random set of iOS apps to decompile and view their included libraries. Its amazing how much tracking is going on. One interesting that I recall was a Bluetooth library in a convenience store app. Seems like they had Bluetooth beacons around there store and it would use the phone to track you as you walked through the store.
I recall the CVS app requesting Bluetooth permissions when I installed it. I can imagine them implementing something like this, but couldn't they just passively listen for Bluetooth beacons from people's phones using the devices in the store, without needing the app to be installed on a customers phone?
I suppose I'm not familiar enough with Bluetooth - I figured phones with Bluetooth enabled are constantly sending out some kind of "hello" beacon.
The beacons in the store are pretty dumb, so they can be cheap (on the order of a few dollars each) and plentiful, moving the real logic of tracking to the app.
You're correct in that it could be reversed and the BLE radios in the store could track the phones instead, but then they'd need far more intelligence and network connectivity, which would make them more expensive and in turn they'd be fewer of them deployed.
Source: spent the last few years writing code for wireless devices, including BLE beacons.
