I've also thought about that a bit. The way I see it, transgender people definitely are following local cultural terms. Not the ones that they are expected to follow, but still.

What's considered masculine or feminine isn't standard across different cultural contexts either. For example, wearing skirts or pink aren't exclusively feminine. In a western context they currently are, so that's why western MTFs are currently inclined to wear those.

However, that wasn't always the case. If the same person had been born a few centuries ago, pink would not have meant the same thing, and they they would have probably felt differently about that color. Also, what westerners would consider a skirt these days, can be a masculine or gender neutral piece of clothing in other cultures. Even today, there are place where mean wear something that westerners would call a skirt.