They do/can, but it's not like you physically look like the opposite gender the moment that you decide you were assigned the wrong gender. People will give you looks or get upset if you look like a dude barging into the women's toilets, so (from what I've heard) it's a struggle during the transition period where you feel like you belong in one place but society wants you in another. Unisex toilets make this easy. I'm not familiar with toilets specifically reserved for trans people but I assume unisex is what's being referred to