Well, for one, ball pythons do not need vertical space as they are not tree dwelling snakes. They like to stay on the ground and hide. You will waste alot of space by putting them in a high cage. My tubs are only 6inches high and they work fine. The amount of floor space they get in a large tub is enough for them. The reason fish tanks are not suitable for bps is because they are "big" but if you compare the floor space, they are no larger than a 41qt plastic tub used for adult bps. Plus inside a closed sided rack, less light is allowed in. And those are the reasons i use a tubs over tanks