The thing is, I'm generally friends with gender non-conforming people because I've always been a bit that way myself, and a bit of an outsider. It's the entire reason I've spent two decades with predominantly gay friends, and I spend 7 years in a same sex relationship.
People always provide these specific examples of trans people who "pass" and say, which toilet do you think *they* should use, like it's some gotcha. I imagine the majority of transsexuals who transitioned in the late 20th century pass reasonably well. Age helps, I think, but as has been explained by someone far more knowledgeable than me in this thread, with personal experience, the criteria for medical transition were much stricter back then. I'm happy to be corrected if I'm wrong, but in those days I don't think transition would have been recommended to those who didn't stand any realistic chance of passing as or being able to assimilate as the opposite sex. So it's a redundant point really, if someone passes and isn't drawing attention to themselves then nobody is going to notice them, whatever they do.
The point here is that there are a lot of trans people now whose entire goal in transitioning is to be noticed.