Mature response there Clare! You remind me of the chief of the CSA who effectively stated there were no bad mothers, only bad fathers on telly a few years ago.
Some of us supervise our kids when they are doing things that could bring them to harm. They have opportunity to do and view things that they shouldn't, but understand that there are consequences _when_ they are caught.
Let me ask you a question, as it's a debate I was having with the wife;
Kid A does something wrong, so you ban them from the Internet for a week.
When they come home with homework saying "research X on the net", do you relax the ban? Me, I don't. I'll drive them to the Library and they can research it the old fashioned way, if the teacher has an issue with that they can speak to me about it.
When they understand that it's not worth the punishment, they become less inclined to do it in the first place. There'll always be transgressions (we were all teenagers once!), but I find both punishing and explaining the reasons for the rule can be very, very effective.
The thing is, no matter whether it's your kids or someone elses, it's never reasonable to demand that something legal be purged from any resource. Yes, we should be filtering internet in schools, but at home it's your connection, your responsibility.
I'd have much more sympathy if you were saying the ISP's should provide some customers with a restricted version of the internet, at the cost of those customers. Demanding wholescale filtering at the cost of every internet user just isn't reasonable or fair. Why should those without kids, or indeed those who put more effort into disciplining their kids pay for those that don't?
I've said it before, I and many others are often quite happy to give up our time and show people how to set up effective filters at the home level. Sure, they don't catch everything, but nor would a Government mandated filter. But then, if you're that worried, use a whitelist!