Can someone tell me why this wouldn't work as a snake rack?

[Archimedes]

Mounting heat would be your first issue. None of the separations thick enough to properly disperse heat would fit properly in this thing. Heat tape can't be exposed to the critter inside, so if you put it on the bottom of the middle rack, for example, the snake in the one below would still be able to touch the tape on its own ceiling.

Seems like you'd be paying a lot more than $12 in order to make it work like one would hope.

EDIT: Also, I have the suspicion that they would warp in any kind of direct application of heat. Perhaps not with the proper heat levels, but if a thermostat goes haywire, burning/melting plastic is the least of your problems.