Synne, I think you know this already, given your comment earlier, but here you go. https://helloclue.com/articles.....-word-lady
Irina, the article I just linked does mention “ladies room” as a euphemism for toilet, but doesn’t touch on the point you made—the refinement suggested by “ladies” does indeed point to there being other women who are lesser.
Not sure annagybe opted in to this detour on her thread though, so maybe anyone wanting to discuss it further could start a new thread. One connection to this thread, though, is that the “refinement” indicated by the term “ladies” frequently includes taking up less space—crossing your legs, wearing tight skirts & shoes that make it hard to take big steps, speaking loudly, etc, so larger women might be subject to prejudicial glances when the question of being ladylike comes up. Instead of including more people in this nonsense, I’d prefer to get rid of the term “lady” altogether.