This is a really basic question, and it relates to the slippery to-ing and fro-ing that TRAs have engaged in.
Originally it was TWA100%W and you are a transphobic bigot if you say that a transwoman is in any way less a woman than a natal woman.
So women, transwomen, all one big happy female sex.
And since transwomen are 100% women, they must of course use the spaces designated for women. Because they belong to the female sex.
Now the discourse seems to have switched to 'We know we haven't actually changed sex'[which they must have belatedly accepted as impossible] we acknowledge that we are still male [female in the case of transmen] we have just changed our gender, and how we present ourselves.'
The problem with that is that facilities are segregated on the basis of biological sex not gender, so, as FranticSemantics asks, what is the rationale for transpeople declining to use the facilities and services designated for people of the sex that they acknowledge they belong to?
ps Thanks buffyajp, that egregious and unwarranted tirade from Ymiryboo was directed at me. But don't worry, I can take it, I know who it reflects worst on, and it's not me