Did you forget about Speeding or the 1001 other traffic offences? Does anyone observe proper following distance for every second of every trip?

I suspect if you wanted to harass your ex-wife, or a dissident, then overhead footage of their car for a few hours would provide a multitude of crimes.

Sure, if you actually prosecuted everyone that's one thing, but selective enforcement plus mass surveillance is a very powerful and easy to abuse tool and you don't need anywhere near 100% coverage to make this effective.