I can sum it up in one word:
Legality.
"Trust" has little or nothing to do with it, actually. The vast majority of 17-year-olds are quite capable of watching themselves and behaving without "babysitting." Not only do I agree, but I can virtually guarantee you most of the other staff does as well.
However, the problem here is that it's not really our call. We have to implement the minor policies we do so that we can do things like convince the hotel to let us have the con there, purchase insurance for the con, show specific materials at the con - basically we have to have said minors policy in place so that we can have the convention at all. Without the policy, we're a lawsuit waiting to happen.
I understand that it's a pain in the neck, and despite the fact that most (if not all) of us on staff are immune to it personally, we do feel badly for it. But it's honestly the only way we can afford to put on the convention. If there weren't a legal issue, we likely wouldn't care nearly as much. But I don't think anyone on the con staff can afford to get sued, so that's kind of the look we have to take on this.
We really can't blame the hotel, as they have their own legal issues to deal with, and we have to follow the rules. So honestly, if you want someone to blame, I'd go after the lawyers. It's always their fault anyway, this time we just have proof.
PezCat