but, c'mon, how are you going to argue you're a mam at that point?

Firstly, funny typo. Secondly, you act like logic plays any part of this. Anyone, male or female, pretending to be the other sex is completely illogical. The whole thing is pointless nonsense.

MtF is trying to reverse this process, which is why they never pass. It's easy to make a woman grow a beard, much harded to make a bald man grow hair on his head.

Sex goes so far beyond hair, though. Also, due to musculature, women trying to be men is often super obvious too. Beards are just a great first level shield. It's basically cheating, but still doesn't usually result in a passing tranny. Having a beard will potentially make a woman pass as a man...at a very quick glance. Past that, there are still often problems. It doesn't help that a lot of the female trannies are slim and short. They gave up on presenting as women to present as very effeminate manlets. i.e. a massive downgrade, in every conceivable way.