> I perceive that they often get lumped into a third category (that isn't male or female)
This is what I mean by the "uncanny valley of gender". Some people, btw, do identify as non-binary and intentionally wish to be seen as neither male nor female. For most people, even transgender ones such as myself, people pick a gender and then unconsciously roll with that in how they relate. When people can't figure out which way to relate, it can make them uncomfortable and cause friction.
> Strangers will be completely natural towards a non-obvious transsexual (where acquantances might not), but then a stranger that becomes a friend will struggle later when they find out they have been "deceived" (which subjectively can't be argued with?). Surely that must cause a lot of friction.
They haven't been deceived! I am a woman, and the type of woman I am is transgender. While it does surprise people, in my experience, it's just kind of an interesting point and then we move on. If it's not a sexual context it really has nothing to do with anything, and so people don't care - they just keep using script they initially picked. Similar to my age - most people think I'm in my 20s, but I'm in my late 30s. They're surprised, but it doesn't change anything so we go on.
> As far as the study went, they would have to find a subgroup that worked as female (or v.v.) without anyone at work knowing or finding out (remaining cryptic at all times). Even then, there is a sampling bias for only those people that act on their feelings and have major surgery, and presumably a major emotional disruption to life for most of those.
This is very true. Transgender people have to feel that they can transition, and a great many don't. I haven't seen any study (and I'm not sure how you'd even construct one) between transgender people who seek transition and those that don't. I definitely live in a much more acceptable environment (in San Francisco) and had the financial, social, and emotional means to do it. A lot of people lack in some of those areas and suffer, sometimes greatly as a result. Access to transgender medicine varies tremendously.
> Is the divide wider than that between a "pretty" woman and an "ugly" one (sorry again, awful word choice, but I don't know how to rewrite that so the meaning stays clear).
I would say yes. Again, it's (in my perception) that uncanny valley of gender. An unattractive woman is still seen as a woman (though her social value is often greatly diminished by it). Whereas non-passable transwomen people aren't clear how to relate to, and it makes them feel uncomfortable.
> sorry if transsexuals is an offensive term, I'm using what my peer group would use, and I have no idea how to safely use the words you use.
Transsexual is a term that's dated to the point where it comes off as ignorant. We use "Transgender" as a blanket, inclusive term (not everyone changes their genitals, which is what makes it preferable to "transsexual").