We have heard many times that gender and sex are different. Many claim that gender is a social construct and sex is biological and determined by your genitalia.

A lot of the people who claim gender and sex are different support gender-neutral bathrooms, but think of this:

Bathrooms for men have urinals, whereas ones for females don't. That is because men have penises, and women don't. So we can come to the conclusion that bathrooms are actually designed for SEX and not GENDER.

So, why do these people ask for gender-neutral bathrooms instead of sex-neutral bathrooms? If gender is not related to genitalia, then wouldn't all bathrooms be gender-neutral by default?