You know, it's funny this gets brought up. Up until 10 years ago, we had a local drive-in theater that played porn. I do not know how they were able to do it but they were famous for it.
I would have to add that, if you want to watch pornagraphy in the ol' family cruiser, why not? Now why you would want to in the first place is beyond me! I get distracted by the hot chick in traffic, I don't need nipples and kitties showing inside the car. I don't think I could explain it to the cop after the accident.
Now it is and should be illegal to have a video playing within the drivers clear line of sight. There is no reason a driver has to watch a show while doing 75 down an expressway. As far as the kids go, I think that they won't be scared for life because of it. Where do you cut it off; NC-17, R, PG-13...Tom & Jerry because it's too violent or maybe that Japanese cartoon several years ago that used to give kids seizures when it would show some "power-up" action in the story.
You're not allowed to smoke in public but you can smoke in your car, so if someone is able to look in your car and watch what's playing in the back seat, does that mean that the inside of your car is public domain governed by public law. Are we not going to be able to smoke alone in our cars now. Where do they stop when your car is no longer private property; your apartment, house, your person?
It's just my opinion, according to my wife, it's usually wrong...