I have plenty of evidence that I am a man; anyone who wants to investigate can find that evidence (though I’d prefer them to get my permission first!). But if I said I identified as a woman, what evidence could I provide, or what evidence could anyone find, that I am a woman? Is there anything at all, other than my say so, that demonstrates that I am a woman?
This is, of course, a rhetorical question. But what evidence does trans identity theory require? None at all?