it's interesting (genuinely interesting, not in a passive aggressive way) that you'd not feel uncomfortable being in a changing room/toilet with a transwoman who 'passes' and I assume this means you might be uncomfortable with a trans woman who doesn't look so feminine?
I don't think it's strange in any way at all. Of course I feel much more comfortable if a person looks like a woman. I can't see people's chromosomes, so I go by sight. If a trans woman passes, that means people think she is a biological woman and therefore discomfort would probably never enter their minds because they would have no idea that said person was trans.
As for voice, Paris has an extremely feminine voice, no adams apple and looks no different to biological women who have larger bone structure etc. On the other hand, someone like Jane Fae is very obviously male.
It sounds superficial to go on looks etc and I am not comfortable about it, but at the end of the day, that's what people do. We know people are men or women by sight. Very rarely, it's possible to modify the body to such an extent that it's largely indistinguishable from the opposite sex, and then we naturally think it is the opposite sex.