Tech adds phone tracking to license plate readers, associating devices with cars (theconversation.com)

SignalTrace, a system marketed by the security company Leonardo, is designed to work alongside automatic license plate readers. The company says it can recognize groups of consumer devices that regularly move together, then associate them with license plate records and time-stamped locations. The pattern can then be searched even when a police investigator does not know the plate number

How is it tracking them, by faking base stations (should be illegal) - or Wifi + Bluetooth ?

Do we get to a point where everyone has to exercise opsec and have their phones completely off a lot of the time and especially when travelling ?