Right but SignalTrace isn't just looking at Bluetooth MACs, they look at Wifi, TPMS, RFID, and anything else putting out a signal.
Say you stop at a bank that has one of these systems and it grabs your plates and TPMS sensor IDs. You rob the bank while wearing a mask and speed off in the car. The plates were stolen so you pull off quickly and ditch them for another stolen set. However, just the other day, the bank caught you on their system while you were casing it without stolen plates and they can match the TPMS to the real plates and know who you are (or at least who owns the car) and the cops get an alert to look for a specific car with plates X or Y.
Or you're on foot and commit a crime while hiding your face. Your phone gets picked up on the system. They don't know who you are yet but if there are enough systems in an area, the cops have a 15 minute window of knowing where your phone is. Machine vision looks for someone matching your appearance and you're continuously tracked even if your phone's MAC changes. Even if you run into a public restroom to change your clothes, they can still associate your new appearance with your phone if the timing is right.
Right, but the mac is randomized every 15 min, which makes tracking hard to pull off.