Zoo animals are also under a level of scrutiny you might be surprised to learn about. In addition to the patrons walking around the zoo all day, several employees will work behind the scenes, checking the animals, feeding them, weighing them, observing them from the outside, and even rotating them out with other hidden stock in some cases when they even suspect a problem. I have had the opportunity on a few occasions to visit a wonderful lady who works in the Smithsonian National Zoo, and she showed us around behind the cages. You really would never realize how much attention is paid to these animals unless you had been back there yourself and seen the detailed logs they keep. You could never hope to provide such attention to detail to your own collection in part due to the funding and partly due to the volume of staff. This is why they can be successful housing multiple snakes together.