There is a sticker on one of the machines that adorn our laundry room. It says "minors are prohibited to use this machine".
If you do any kind of digging on this prohibition, though, you'll soon find that the reason for this prohibition isn't any given law, rule or ordinance. You'll also find that there are plenty of minors who, despite the sticker, use the machine to their laundried content, without anyone giving it a second thought.
In order to understand this, we must look at this prohibition as a speech act rather than as a regulation. It is not there to say "minors are not allowed to use this thing". Rather, it is there to say "hey, look, we told everyone that minors can't use this thing, and yet they did it anyway. It's out of our hands."
So what is on the surface a prohibition, is actually the opposite: a legal disclaimer.
Rhetoric in all things.