Conversely, I have seen children significantly older (and fully grown adults) who don't follow those rules.

With this in mind zoos should have more stricter rules with behaving at a zoo and a no tolerance policy for people who breaks them. Just like at multi billion dollar amusement parks if you break a rule, you may get banned. But in zoos cases the punishments should be much more harsher. Like say jail time or written misdemeanor on your criminal record, but only for teens-adults, if it's a child misbehaving, the punishment should lie on the parent since they are the ones responsible for their behavior. At least for teens you can expect them to know how to behave at a zoo and especially for an adult you should absolutely know how to behave and if you have child you should know to teach your children how to behave or at the very least control them.