Not to mention the possibility of requiring pedestrians and cyclists to also be connected to the same network. Anyone with access to the automotive network could track any pedestrian who passes by the vicinity of a road.

It's hard to think of a good blend of traffic safety, privacy guarantees, and resistance to bad-actors. Having/avoiding persistent identification is certainly a factor.

Perhaps one approach would be to declare that automated systems are responsible for determining the position/speed of everything around them using regular sensors, but may elect to take hints from anonymous "notice me" marks or beacons.