> It's impossible to ban adult content in a cost effective way without also banning a large amount of legitimate art.

Are you saying that adult content is not legitimate art?

If so, I think you may be part of the problem, not the solution. English is not my first language, so please correct me if I am wrong.

By adult content, most of us think "porn". But as has been said, there's also violence and other things that some culture do not want their children exposed to.

There's no way to ban nudity or other things one may dislike without having to put some kind of filters in place. And once those filters are in place, they are abused to filter legitimate content. Every. Single. Time.

We have to rely on education, the best filter is in our brains. That's the cost to real freedom of speech.