[Fins]

The umber of trans people harassing somebody in the bathroom, or otherwise, is probably minuscule enough, and indeed there are laws that deal with that.

But you seem to be intentionally overlooking GP's main point -- people (dare I say most people, probably) have that strange hangup that they really prefer to visit the restroom with people of the same biological gender.

And before somebody comes back with "at some point people did not want to share bathroom with people of a different race", there was a movement to make people see folks of other color as fully human. There is no movement to make people accept seeing naked people with different genitalia.

(added) I don't think anyone is arguing seriously that transsexuals should not use public restrooms, period. But which restroom to use isn't quite as simple as "whatever gender they identify with", unless you believe that others have absolutely no say in the matter.