I'm surprised nobody has mentioned one of the biggest issues with general acceptance of this system:

Police will be able to force anyone to pull over anywhere, at any time, and for any or no reason.

Even though they can do that now, people still decide to pull over. They are not forced to.

And what if there becomes a database that police forces compile, showing the history of movements of everyone? That database could potentially be leaked.

I think the privacy implications of this should get at least some thought.