I did this.
Dr wears shorts too. No one's taken an upskirt photo but she doesn't want people to see her pants and of course kids do snigger when people do hand stands and pants are on show.
I used to do it as it was an extra layer when dealing with periods plus my old schools didn't allow trousers for girls 
Anyone who thinks they can find a pair that fit, don't itch her And don't need to have the adjustable waists pulled yo which then cause immense irritation where it's bunched and the buttons rub they are welcome to come here and try before deciding skirts should be banned. And I have tried many suggestions when I started a thread
How about we tech kids and biys in particular to grow up we all wear pants there's no need to point and laugh. And we certainly should be teaching biys to be respectful and not take photos. Sooner that's a crime the better.
If we could get rid of uniform altogether id be happy.