While I feel like the beacon tracking SDKs in apps are as slimy as going the other way round, those SDKs aren’t watching for your device’s beacon. They listen for BLE beacons with known addresses the company has place on their premises and use that to determine you’ve been to that particular location. I’m sure some of them are doing it at a larger scale and tracking all the beacons you see to provide a view on all the places you’ve been.
Almost all devices you’re carrying with you will regularly rotate the ID they transmit in order to avoid correlation, so reading those beacons in a location can’t really be used for much beyond rough numbers of devices.
> Almost all devices you’re carrying with you will regularly rotate the ID they transmit in order to avoid correlation, so reading those beacons in a location can’t really be used for much beyond rough numbers of devices.
Maybe that's true for those devices, but it doesn't protect you if your apps are tracking beacons as you encounter them in the wild. Your mac changing doesn't change that it saw a beacon somewhere, and attached that to your account in the app you're signed in.
Turns out, that's exactly what they do...
> But these apps may also be tracking you in less obvious ways. As the New York Times noted last June, many retailers deploy Bluetooth “beacons” throughout stores. If you have the store’s app installed on your device, the beacons send it signals. The app then knows where in the store you are and sends you information (like coupons or store maps) specific to that location. *But this also means the app can track your movements as you pass by the beacons. Depending on where and how the beacons are placed, your location can be measured in inches.* Some device manufacturers have wised up to this practice; for instance, the iPhone’s newest operating system requires apps to get your permission to use Bluetooth.
Almost all devices you’re carrying with you will regularly rotate the ID they transmit in order to avoid correlation, so reading those beacons in a location can’t really be used for much beyond rough numbers of devices.