The thing is, in the USA, there is a minimum wage, and waiters specifically are allowed to receive a wage much lower than the normal minimum because they're exp

The thing is, in the USA, there is a minimum wage, and waiters specifically are allowed to receive a wage much lower than the normal minimum because they're expected to subsist off tips. Other non-tipped restaurant employees get paid an actual wage for their labor. So if the waitress received a windfall, it's only fair that she get to keep it and not be forced to share with the other fully compensated staff.