Why? What is the underlying reason for that? Is it different if your (hypothetical?) son of the same age might have a woman (regardless of dress) in with him?
I'm genuinely curious.
But, if the issue is whether we should have separate bathrooms for the genders, let's have that conversation instead of forcing it on society in the guise of discrimination.
I'm confused... in bathrooms in the US, you don't have cubicles that shut+lock? You strip naked in public areas? In my country, we have cubicles that lock and people pull their clothes back on before unlocking them.
Also, like... why's it ok for her to see strange cis women taking a shit, in case you actually do all shit in the open?