Yeah girls facilities being better in almost every way to the point of getting private showers while boys are screwed totally isn't sexist at all. They're Seperate But Equal. Women are just more equal than men, so it's a legitimate rap-sorry-discrimination.
Women already get astoundingly preferential treatment throughout the entire education system, which is reflected in their utter domination of virtually every measurable aspect of education up to and including being nearly 2/3rds of college graduates. Meanwhile men are drugged more, punished more and more severely, graded worse, and systematically excluded from opportunities handed to girls on a silver platter.
The harm is there. The harm is proven. It's reflected in graduation rates.