>> In addition they are assuming perfect knowledge. The transwomen that don't fit their assumptions, they wouldn't see as trans, just as women, which they would assume were all cis. <<

Likely so.

>> Later, I realized seeing her washing up in the ladies I entered, she must not be a transman. (or at least not one disconcerted using the ladiesroom) <<

Bathroom use is a huge issue for transfolk. Often they are required to use the one that matches their current genitals, not their gender. Some places they're not allowed to use either.

This is why I'm in favor of having a unisex facility and/or a family bathroom available.