Guess what transwomen are females born female.
I actually wouldn't be against requiring medical documentation though if the American health system were not so rigged against the poor. If all of us who needed to see a therapist and doctor, needed to get our other medical treatments for this condition, were able to even without having money, then I wouldn't mind presenting a letter stating such if some cop asked and then left it alone.
Of course, all the above is a great deal of ifs, and who knows how long it will take for the health system to be fixed. And no waiting until it is is unacceptable.