Is this a California “thing?”

So I like to look at people’s avatar closely because you can learn a lot from them.

One thing I’ve noticed is not all but a lot of people parking their cars inside their garages on large rugs come from California.

Am I off base or is this a law or just keeping the concrete clean due to their environmental laws? A trend? Or a merely a coincidence? Here in New England it would just attract bugs and mice
No judgement just observation.
Joe