Which intimates it was allowed but that studio policies, it again intimates, might be responsible. It does say one single TV series never showed a toilet, but only a tank.
Interesting taboo nonetheless.
I always thought it was just not done because it generally isn't moving a story on to show someone on the toilet. Books don't usually mention characters using the toilet either. I've played videogames with an eating mechanic but never one where you needed to defecate (though Sims could when I last played that).
