A lot of the discrimination faced by women (all women) is based on assumptions about our biology
Weeeeeell that is mostly true, but the problem is that the vast majority of male-bodied transwomen don't pass, instead they look like a man who hopes everyone will treat him like a 6 yo fairy princess. So no one is treating him as they would a real woman, instead they're patronizing him as if he's an insane manbaby and he doesn't understand the difference.
But secondly, he'll never worry about getting pregnant, or needing an abortion, or not getting hired because he might take maternity leave, or being raped by somebody much bigger. Nobody ever expects him to shut up and make coffee, or volunteer to bake a cake for someone's birthday, or be supportive when others are having a rough patch, or take care of elderly parents when they are sick, etc etc etc. He's exempt from all that exhausting emotional labor that is expected of every woman because nobody thinks he's a woman.
A young trans girl does not have the same experience growing up as a young cis boy, even if they’re both treated by the people around them as young boys. If you’re treated as something you’re not, you’re not going to have the same experience as people who are treated as something they are.
First he claims to pass, then he claims to not pass. Make up your mind. And you can't possibly have the same experiences as a girl when you admit that other people are NOT treating you like a girl.
Trans people and cis women have a huge amount of common ground
Considering that I object quite strenuously to your dick in my shower whereas you keep trying to intrude in rather a rapey way despite my objections, no sweetie, we only have as much in common as any rapist and victim.