Galt. The law says that a person must go to the bathroom that is listed on their birth certificate.
Let's go through this step by step. Imagine a person named Stacy. She was born a girl, played with dolls, had a pink room, etc. When she became a teenager, she developed boobs, had a sex drive, and even had sex with guys.
Then, later in life, she changed. She started desiring to have sex with women. But, she didn't just want to be a lesbian. She wanted to become a guy. So, she had her breasts reduced. She had her junk removed and a vagina installed (still don't know how, but they do it). She had hormone therapy so that she could start growing a beard.
5 years later, she goes by the name John. She's got a beard, hits on women in bars, takes them home for sex, speaks with a deep voice, etc. All outward and even actions appear that John is-and-always-was a man.
But, in NC, John has to go to the ladies bathroom.
So, let's say John is sitting next to you and your wife at a football game. He's really funny, so you and your wife have enjoyed having him there, as he's making the game more enjoyable. Halftime comes, and everyone goes to the bathroom. Your wife comes back, and she looks upset. Turns out, John had gone and stood right behind her in line, then gone into the stall right next to your wife, peeing while standing up, with the door to the stall wide open. Now, your wife doesn't want to sit near or talk to John.
That's what is happening.