No. There first thought is how to keep the animal from escaping/safety of the handlers. Second (now day, not a concern in the past) is design an environment to suppose the mental and physical health of the animal. Third is how the visitors can view the animal safely. Many enclosure depend on the intelligence of visitor not to violate the post rules in order to give clear views to the animals.
There is only so much safety you can add before visitors complain they can't see the animals. The compromise is zoo lower fences and the public promises not to jump over them.
You worried about kids getting into the exhibits? Most of the time they end up in the closures because of dumb ass parents like this:
Can't find it now, but there was a case where the exhibit had an 6f+ chain link fence and the parent over the top so their kids could see better. Of course the kid fell in and they blamed the zoo.
How do you stop idiots like this? Age restrictions for kids? Intelligence test (for the parents). Electrified fences to keep the humans back? A guard at every pit writing tickets to violators?