Cigarette smoke is different than car fumes. Secondhand smoke can still cause cancer, over enough time.
My main problem is smoking in a care, with kids, with the windows "up," not down. Having asthma, when my uncle would smoke with the windows up it was like slow suffocation.
So no, I see no problem with having government fine irresponsible parents who do this sort of crap. If the windows are down, that changes things.
when they legalize marijuana will that be illegal to smoke while the windows are up too?