some bathrooms have a few small rooms instead of stalls and sometimes have sinks inside too.
But this is usually just one of them and in smaller irregular bathrooms like a restaurant bathroom or so. Your average facility big bathroom with stalls rarely has this.
If there were small sinks, someone would try to climb it and destroy it, guaranteed. Also it costs money and it is sorts of useless to have them, and it takes up a lot of space.
Anyway, how retarded are you if you get shit on your hands when using toilet paper?
In asian countries they have ass water hoses in the stalls so you can use those I guess.