The men’s room in my section of the building has two sinks; each sink has a soap dispenser. The soap on the left is completely empty, and the soap on the right is almost totally full. What does this say? People use the sink on the left far more often. That’s not all that hard to understand; the water pressure on the right sink sucks. Given that each sink sees the same maintenance at the same time, it also says that either there’s only ever one person using the sinks at a time, or that people are so unhappy with the sink on the right that they’re willing to wait for the other sink to become available before washing their hands.
I don’t think it’s particularly likely that people would stand around and wait to use one sink given that the other was unoccupied. I can’t give a specific reason, aside from that it would be “weird” and maybe “creepy”, but whatever the case generally socially unacceptable. It stands to reason, then, that either we only ever have one person using the restroom at a time, or that people will deliberately stagger themselves as they depart from the urinal or the toilet to wash their hands.
We must all be embarrassed at the pure, concentrated evil that we’ve left behind.