One thing that's always kind of bugged me in the game is the way the guests seem more motivated by the food and beverages than anything else. Case in point, I've created a number of nice underground viewing grottoes for aquatic animals, but the guests tend to ignore them unless I put vending machines down there as well. Then they buy food and leave and don't stay to watch the sea lions or whatever, even if the animals are putting on a great underwater show in front of the viewing area. Likewise, guests will go to areas of the zoo without any habitats or exhibits if I put food courts there. I am guessing the extreme food motivation of the guests, paired with the lack of drinking fountains (not something allowed in real zoos) is to generate more cash? Obviously, real zoos make a lot of money off concessions, but not everyone comes to a zoo just to eat their way from one snack bar to the next. People seem to need to eat and drink more than they even need to use the restrooms.