Yes, tubs are very good.
Many people prefer tanks for their visual appeal and they do not have problems with their snakes. 20 gallons may be enough for some snakes, but a full grown ball python would need a 30 wide in my experience. I have a big male in a 30 wide right now and he is very content. Yes, with a tank one must be more mindful of husbandry challenges present with glass and high amounts of heat and humidity loss. There are several simple options for overcoming these difficulties however with a little planning beforehand.