In socal people might not even use license plates at all. Some people mask them with a towel or something like that. Some run paper dealership plates which I guess don't need to have any license number on them at all, just the dealer logo. Others just take them off and drive. I've seen plates that were sanded clean and with different numbers stuck on them that don't match then indented numbers.

And then of course all the texas plates. No, it isn't just visitors from texas. Texas has a cool loophole where there is no registration information on the plate, it is on a little sticker on the dashboard. As such, there are a dozen plus cars that have been regulars in my neighborhood for years with texas plates, with some several years old sticker on their dashboard.

It is kind of surprising that they don't get hit with a huge ticket for failing to register their car after 20 days. Some even park on the street quite brazenly. But maybe that shows how these systems are, today at least, very poorly connected between states. I've even seen a car being sold locally where the owner openly admits it was never registered or smogged, and they used it as their local neighborhood runabout just rolling the dice that they would not get pulled over. Just an aspect of the driving culture.