HairyBallTheorem Supermatch I think you're buying into the obfustication pushed by a lot of TRAs, namely that telling someone's biological sex is some sort of arcane scientific/medical specialisation that can only be carried out by sequencing someone's DNA. Whereas in actual fact the vast majority of people have no problem whatsoever identifying other people's biological sex. It is after all how our species manages to reproduce without going extinct.
Yes you can usually tell someone's biological sex. You can tell all sorts of things about a person that if you vocalised about them would be rude.
Medicine and science has decided that some people need to transition and live as the opposite sex to which they were biologically born, in order to be (more) healthy and functioning. They identify as such in a way that so far, medicine and science has not been able to change. Doctors and the legal system in most countries have already established that. It may seem like 'having to play along' to you but it is considered a humane response by most.
I'm not saying we all need to be nice obedient compliant little things but most people have a standard of decency and respect towards other human beings that includes avoiding unnecessary cruelty and supporting people to reach their full potential.
So you can tell that probably most (not all) trans people were born a different sex. So what? You can see that some people are disabled or facially disfigured or short stature. That doesn't mean you have to keep referring to it in an offensive way. By deliberately using the other gender you are doing that.
AAngryAttackKittens
Well, no, the legal system does not in fact have the ability to change a person's biological sex
But it does, in fact, have the ability to change a person's legal sex. And our rights are those that are enshrined in law. That is true in the vast majority of civilised countries. For both points.