You'd probably just see a large uptick in people obfuscating their plates (which is much easier with US-style plates than European-style ones).

That's what's happened in NYC. All the drivers who go out intending to blatantly violate the law just started making it so their plates can't be read (or are outright missing) and don't care about the cameras at all.

As someone much further north, unless I just came out of the car wash, my plates are basically illegible 4-6 months a year because of the heavy level of salt/sand/crap on the road in winter.

I don't think you're getting away from requiring a high level of traffic stops to influence driver behavior significantly.