I've been curious about this for a while now, how do US number (licence) plates work?

In the UK they uniquely identify the vehicle which in turn gives traceability to the registered owner.

I've seen on this board two 'empeg' number plates and now a highly desirable and I guess duplicable 'h4xor' plate and was wondering.....
If you get seen speeding or knocking little old ladies down, how are the police gonna get ya'? I presume they can and do but how?