Try because men are pretty much used to some entitled chick deciding that she can enter the mens because the q for the womens is too long...That combined with transmen can pass better. Combine that with men being generally a lot less risk adverse than women and it will lead to a lot of fucks not given about it. The only time you will generally get pushback is when the woman in question starts trying to police the mens toilets.

But yeah transmen that complain because being treated like a man is worse than being treated like a woman do my fucking head in especially when their solution is "men should act more like women"...