SignalTrace “links devices that regularly travel together, correlating them to license plate.” It is a surveillance product that will sweep up and add all sorts of Bluetooth and other data to license plate readers, linking specific devices—and people—to cars.
I mean, the real sin here is from the Bluetooth SIG. If you make a radio protocol that broadcasts a unique identifier, it’s going to be abused sooner or later.
Google and Apple already know where Bluetooth devices have traveled if an iOS or Android phone using Location Services has come near them at any point.
Other people, like these ALPR guys, can probably harvest a little more data from users of Bluetooth devices, but they aren’t going to be the most meaningful harvester, as they have far fewer collection points.