Body heat is one thing.
These people have very different attitude. They perceive their snakes as units / items / product, anything but wild animals. Some argue that reptiles born in captivity know no better, so it's OK to keep them in small plastic boxes. They do survive, they even breed. With the exception of mass production reptile farmers, I will never understand how can these people derive any pleasure from having reptile collections. Efficiency and easy maintenance seems to be the key word. Where is the sense in keeping large number of animals in such conditions? On many occasions I have been accused of "breeding for profit", I challenge those keepers / breeders any time - what are they in for?
Each to their own but I could never degrade reptiles, not even domestic animals to that level.