Why does this bother you so much if the sign isn't about you?

No one said it was, you decided it was. The sign doesn't mention gender, and further it's about taking photos, not touching people.

I'm really sorry anyone felt entitled to put their hands on your body without your consent. That really sucks. They absolutely should put up signs reminding people to keep their hands to themselves at your old job. I'm guessing the old bats thought they could get away with it because it was wink wink ok with the culture of the place. If people are being touched, the place should make it clear that's not tolerated and then act on it when you report it. The signs might not stop the pervs but maybe they would signal to the 18 year old that your boss would agree that that's never ok, and you should report it and there should be consequences.