Many years ago, around 1997, I visited my campus job center to do research on grad schools. The gal there made me fill out a form. I already had a male name, so that wasn't an issue. But I was so dysphoric by then that I couldn't check gender boxes. Just couldn't do it. I knew I wasn't female, but I didn't feel legally entitled to check the male box. So I always deferred to paralysis and left that field blank.
I later saw that she had checked the F box for me. Usually I don't see the form after I've submitted it. This time I did. My then-partner had to endure a lot of ranting when I got home that day.
Fast forward fifteen years. I'm uninsured now and need a flu shot, so I go to Walgreen's. The pharmacy guy has to fill in my info, so he asks me all sorts of questions: name, birth date, address, phone. He doesn't ask my sex, but I later have to verify that all information is correct. I see that he has checked the M box. Automatically. No question.
I started T three and a half years ago, and I'm still bowled over that people read me as unequivocally male.