Yes but how many parents let their children watch 18/15 movies they own or have rented?
I should imagine pornographic websites have disclaimers before you enter...
Yes they are. If they don't understand the subject then they should at least make an effort to learn the basics.
You don't need to be a technical expert to have the computer in the living room with the adults and impose strict policies on the time it is used.
Sure there may be some things the kids can get away with using a setup like this but that's children for you.
However all this takes effort. The easy way is to give little Johnny a laptop and let him do as he pleases because you get some peace and quiet and can watch Eastenders.
You see it every time something bad happens. "Why oh why didn't the Government regulate x - Think of the children"