I don’t understand the distinction. You sit on the bottom of the tub, so clearly it needs to hold as much weight as the toilet does. It also needs to hold the weight of a lot of water.
That said I don’t think plastic tubs are common either. Perhaps a plastic covering around a stronger structure.
The weight might be distributed differently, especially since a tub will usually be filled with water. Also, do modern tubs actually hold anything off the floor, or do they sit flush with it and provide a water-tight container to keep the water off of the ceiling in the room below?
Depends. Your shower base will probably break if it’s not properly supported on sand or cement, but your tub will probably not break unless you dance around on it while it’s empty.
Things happen when bathing babies…
nevermind. zombie
nevermind. zombie.
My first thought also.