@thor
It's multiple factors.
It's boys being able to do the peeing part faster, on account of not having to wipe or sit down for it.
It's urinals being more efficient space wise.
It's girls having smaller bladders and having to go more often.
It's girls going in pairs, and using up twice the space in the bathroom for the same amount of pee.
It's girls doing makeup.
It's girls doing gossip.
It's girls having a cry instead of a pee.