So long as it not obscene many US States allow, at a price, one to design and register a "personal" plate. I frankly don't think it matters much as long as the vehicle is traceable via the registration. What I do dislike is when people break the laws on character size and spacing which makes taking note of a number difficult.
I did once see a "corrupted " plate T055ER ~ that even I would have paid money to own.