It's curious why there are no reverse systems where, when accessing an adult resource, you have to prove that you are a child?

I've seen some forums (mostly political) where you have to prove that you can act like a child to be welcome. So that's kind of like what you're talking about?

(If anyone is offended by this, don't worry, I'm talking about the other side; I'm sure your side is full of reasonable adults who just get a little carried away sometimes.)