The biggest dangers to women and girls in the bathrooms is from heterosexual men. I can't recall an news stories of a real trans person committing any crime in a bathroom. But there certainly have been plenty of news stories of heterosexual men and boys making peep holes from the adjacent store room, placing small cameras, you name it.
I remember a long time ago some guy was caught down inside the accumulation area of a primitive rest stop outhouse. He was wearing waders and had an umbrella.
While we are at it, the biggest dangers to women and girls anywhere, not just bathrooms is heterosexual men. Coaches, clergy, politicians, you name it. Has there ever been a case of a true trans person caught doing anything improper? Doubt it.