Taking the idea and running with it, I’m actually unsure how you’d go about making bicycle registration plates work given the nature of bicycles.
Cars are different, as there’s a large data infrastructure around them, the Police take theft and use reasonably seriously and really very few people make changes much more significant than wheels and tyres, and even then they’re inspected yearly.
I could just about see a rider registration plate working although I have no idea how you’d mandate its physical display as it’d more or less need to be on the rider’s back. Race kit is one thing but general riders aren’t going to have a single item of outerwear that is always the outermost item especially unless we’re banning backpacks as well.
In my mind if this idea was going to fly at all it would need to be something similar to a photo card licence and would be useless unless you stopped the rider and demanded it…