You just don't understand. Have you even met some who was transgender?
Also, for the most part, students are not going to pretend to be transgender just so they go into the toilets for the opposite gender. Also, LGBTQ people should be included in non descrimination policies because so many other groups of people are already included in these policies, why not LGBT students? They exsist and can't change who they are. It does no harm to include them in non decrimination policies.