Why do a lot of you keep your snakes in plastic tubs?

Please don't take that question as judgmental. I am new to this, and still learning the ropes. Just curious, so I ask a lot of questions. I am assuming it has to do with keeping the humidity up. I don't have any issues with the humidity level in a glass tank with a screen top. I just leave a wet towel over 50% of the cage.

Beautiful snake, by the way. I love her colors.