I used to feel the same way about prisoners, but there are plenty of arguments that they’re not slaves. The one that convinced me was that you can’t buy a prisoner, for example. Ditto for children (most of the time).

The trouble about laws involving children is that you’re up against every parent who has a child. By default they’ll err on protection, because our biology says that’s the safest thing to do. But as you say, that’s not always the best approach.

Male circumcision is an interesting one. The correct thing to do isn’t to say "here’s an example of something screwed up" as a way to justify something else; instead, ban the screwed up thing.

Personally, I hope it’ll be banned one day. I once asked my dad whether I was circumcised. He laughed and said haven’t you looked? I still have no idea whether I am. Now I’d rather not know.