system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do single person restrooms often have a male and female one?

I don't understand because it's not like there's gonna be anyone else in the bathroom but you. Also they both have a toilet and sink so there's basically no difference exept if there's a men's urinal, which you don't have to use if you don't want to or can't.
gpt
Both men and women are gross when it comes to public restrooms. That's not something associated to one gender.

I would say the actual answer is that people expect public toilets to have a mens and a womens, societal standards calls for it. If they didn't put labels people would probably complain about men going in after a woman and vice versa. Or they might be confused and constantly ask staff which is which. 

Putting labels on it prevents confusion and prevents complaints.

Short answer, they put labels on them because people expect it.

If anybody were to go to the single person toilet and find no gender label on it, and there was a second toilet, I'd bet there's a significant probability the person checks the second door for a sign to make sure they're not using the wrong one, even though it ultimately doesn't matter.