Placer is one of many, many platforms that do this. Assume any app that requests location permissions is selling your data. Hopefully anonymized.
I suppose I'm not familiar enough with Bluetooth - I figured phones with Bluetooth enabled are constantly sending out some kind of "hello" beacon.
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.