But let's go ahead and agree with you and add number plates to bicycles - ignoring the huge costs incurred by the state - how exactly does that help enforce any laws? Bicycles are to small and light to trigger most red light cameras and to slow for speed cameras. So you're only left with visual enforcement by an officer of the law, which will have to physically stop the offender to issue any fines... which... o, hey... you don't need a number plate for that.
If I don't count minor speeding (<10 mph over), I see a much higher percentage of cyclists breaking the law than cars. I drive through a busy four way stop while commuting and nearly every bicyclist does not stop and about half don't even slow down. I don't think I've ever seen a car just completely blow right through the intersection.
Depending again on location, there's almost definitely laws on indicating turns which I'd say is probably the one I see ignored the most (to cut off the 'I see bicycles not indicating' line, most places have a 'when safe to do so' clause for bicycles).
Also slapping plates on bikes will totally fix the issue of theft. Cars never ever get stolen, because they have plates.
I disagree with your underlying assumptions and your suggestions. What you are suggesting would penalize the sorts of people who rely upon their bicycles to get to work each day.
Ultimately I agree that adding plates is a bit extreme, but I think it's also disingenuous to say there is no problem and ignore them.
Edit: I would also like to note that I'm not commenting on motor vehicles disobeying laws in similar situations, they routinely do, however that does not take away from the fact that there is an issue here as well.
I know that seems weird for people where right on red is illegal, but it's really no different than what happens at a stop sign.
https://www.theguardian.com/cities/2015/oct/27/cyclists-run-...
Johnson and Transport for London requested permission for a trial back in 2009, but it never took place. TfL has concentrated instead on remodelling junctions to allow “early release” (where cyclists get a green light before cars) and “hold the left-turning traffic” (keeping cyclists and cars apart on left turns).
I'm willing to buy an argument that "vehicular cycling" (using the road in a way that's similar to a car) can be safer in certain circumstances and that obeying traffic lights, stop signs, and so on can help cyclists and drivers share the road more safely. I have certainly felt that way when I've cycled in communities that aren't used to many bikes on the road.
On the other hand, the idea that traffic laws are there to protect cyclists just doesn't make sense to me. By and large, traffic laws in the U.S. seem to privilege the material concerns and safety of drivers.
I think traffic laws encourage predictability and predictability leads to safety for everyone -- cars, pedestrians, and cyclists.
Having driven in 3rd world countries a few times where traffic laws were completely ignored, it was always shocking to drive again in the US. Everything seemed so controlled and ordered by comparison.
That said, if you start ticketing people for riding on sidewalks in the suburbs, pretty soon you won't have any bicyclists at all in the suburbs. Drivers are much, much worse on suburban and rural roads in my experience. Not because they're less skilled or less likely to be texting while slapping the kids and fiddling with the radio, but because they're going faster. Downtown they're all stuck in traffic (haha!).