It's really pretty simple. If I have a child living as a female then she uses the ladies room and if they are living as a male he uses the men's room. Both restrooms have stalls. If a person that looks like a male uses the ladies room (or vice versa) that will cause more issues than someone that looks like a female using the ladies room.
I can see there could be some issues in schools, I imagine with some confusion for young people. However, those things should be addressed on an individual basis and with educational information given to affected schools.
The argument that this allows predators into the restrooms is not valid in my opinion. They are already there. Have always been there. Just like there have always been transgender people. Why people think this is something new boggles my mind.
Stop the hate people! Stop the judgement of other human beings that are just trying to get through this life as happy as they can.
Peace and Love.