Yes it is. Ball pythons in the wild live underground and they hunt at night. They like dark, humid, tight-fitting places. They typically don't do well in open tanks, and they get stressed to the point of not eating because they are exposed, don't feel secure, aren't warm enough, and are too dry. People who keep and breed a lot of them keep them in tubs and racks not so they can keep a lot of critters into a small space, but because the snakes thrive in that environment.
Of course, the folks at the pet store won't tell you this because they would rather sell you a heavily marked-up tank than tell you to go to Walmart and buy a Sterilite latchbox for five bucks.
I also don't see where you were sold a thermostat for that under-tank heater. What is the surface temperature of the glass over top of it?