My understanding is that the only thing keeping this from happening is that the data is far more valuable for traffic monitoring than law enforcement. As a trivial example, these cameras can already determine is a vehicle is speeding based on its number plate sightings between any two cameras. They can hence start issuing tickets, no radar or police needed.

However, they've not gone down this path because they are (rightfully) concerned that there would be an instantaneous and severe backlash that could lead to those cameras being banned entirely, which would cripple traffic control.