But are they illegal?
Every once in a while down in these parts, you hear about somebody being arrested for being in the "other" washroom, usually women who got sick of the queue for the women's room. They get arrested for "suspicion of indecent exposure" or "disturbing the peace" or some other bullshit "crime" because I'm aware of no law that forbids mere presence in a washroom designated for the other sex. And they generally get released and swept under the rug, and the cop gets an introduction to reality, because as I mentioned earlier, under the Civil Rights Act of 1964, sex-segregated washrooms are every bit as unlawful as race-segregated washrooms, and nobody wants that headache.
Point is, if this is such an all-fired threat to the decent, honest, Gawd-fearin', hard-workin', right-thinkin' Children of Canada, why hasn't presence in an "other" washroom been a criminal offense for decades? Indecent exposure and sexual assault are, regardless of gender.
That's the ultimate question. If a person goes into any washroom, uses the facilities as intended, and leaves, there's little to no exposure of the naughty bits, so what's the big deal? If that person does something "inappropriate," it's been illegal for decades, so what's the big fat hairy deal?