As my title suggests I know the real reason that there isn't one working toilet in Fallout. It's isn't the fact there was a nuclear war and the sewage systems are no loner functional, or there are no employed cleaners. The real reason that toilets are broken is diarrhea. For two hundred years humans and ghoul alike have been on a diet of Pork and Bean, Cram and Instant Mash. No wonder all the toilets are broken, and what's worse is that people, people like my self can't help but drink out of them. I feel disgusted and I for one will be adding more fiber to my diet and you should too.
They just aren't needed anymore. What with all the deathclaws, cazadores and other terrifying monsters out there, people's bowels have gotten used to taking care of business anywhere, anytime, on a second's notice. Can't have all that ballast slowing you down, when you got a race to win.
"Gimme three steps, gimme three steps mister..."