My home zoo is the San Diego Zoo where all the animals can live outside all year round, but they still have their indoor animals facilities. And even those are hidden. They try to create a natural looking habitat, where staff facilities definitely don’t belong.
Zoos in cooler climates need larger buildings for the indoor animal facilities, so that’s maybe where you get to see more of the staff builings as well. But there are some zoos with huge indoor areas housing several habitats, all designed to look like a real jungle/river scene, for instance. Don’t you think the guests would not complain if they could see all the staff facilities everywhere?
In zoos, if you would see every single staff building, you would complain as well. There is one or the other special building such as animal nurseries, the vet or the elephant care center or similar visible to and visitable by the guests, but in general, the ordinary facility buildings are well hidden. More often than not, the back wall of a habitat is extra high and the buildings are hidden behind that wall, together with the indoor facilities of the animals.
I actually had guests complain that they could see the staff facilities even though they were far enough away and the negative radius didn’t even apply. I was so surprised that I double checked the heatmap. After I hid the buildings behind some trees, they stopped complaining. So apparently, it does make a difference if they can see them or not, or maybe it was a bug.