The whole concept of 'passing' dates back to American slavery times and the Jim Crow era. A black person who could 'pass for white' often did so to avoid slave catchers who would kidnap free blacks, as well as a host of other indignities and later, to avoid discrimination.
'Passing' meant that no one could tell they weren't white. It didn't mean that they had 'gained the respect' of white people or that they were viewed as 'honourary whites'.
So, 'passing' means that no one can tell a transperson wasn't born their target gender.
Being accepted and treated as one's target gender is exactly that 'accepted as target gender', not 'passing'.
