Anyone who has kids, a vindictive bladder, or a digestive system that functions like clockwork knows where the restrooms are and visits before jumping into the next adventure. Office, gas stations, Target, rest stops, port-a-pots at the farmer's market...real world logistics are planned around potties. In SFF worldbuilding? We'll send our fearless posse into the glacial canyon, covered in eighteen pelts of wild beasts they slaughtered and skinned with their own hands...and no one is concerned about copping a squat in sub-zero temperatures.
Or toilet paper.
How many of our fearless heroes are running the gantlet with grungy butt?
Now, showers, on the other hand, they are the literary stars of the bathroom. Giggity-giggity.