Sometimes the reason a fence exists is because the person who put it there was some combination of a) an idiot, b) extremely confused, or c) not qualified to construct fences.

Also, in software, you may find the fence sometimes exists in higher dimensions than the usual three, can turn invisible for part of its length, and occasionally exists but is four inches tall and blocks only mice. And it may also be designed, at least in part, by a blind idiot god called ChatGPT on whose altar consciousness itself is sacrificed. At this point it's worth considering whether keeping the fence around is worse than letting the bull out.