Don't know about California but running a car without a catalytic converter while stationary and having kids in it would imho be child abuse via poisoning. And those enabling it should be liable.
In 1975, it would be normal for an 18 year old mother to drive around with her unbelted child in the front seat, a beer in the cup holder, and a lit cigarette in her mouth, and then leave the child alone in the car while she ran errands.
Today, that would constitute 6 or 7 different crimes.