> She regularly has nights where she makes $300+ in tips
How regularly does she have nights where she doesn't make $300+ in tips, and what does her nightly pay average out to over the course of a month?
I'm sure it's probably more than the minimum wage, but that's because of the appallingly low minimum wage in the US.
Compare with say Australia, where the minimum wage for restaurant staff is reasonable, with extra loading for late night, early morning, weekend and public holidays, and you have a situation where an experienced waiter working in a regular (e.g. not too upscale) restaurant can bring home close to $100 for a 4 hour shift (more on weekends and late night shifts), and more if working in an upscale restaurant.
I know people claim that raising the minimum wage will put restaurants out of business and so on, but the situation in Australia and other countries disproves that because despite a high minimum wage, Australia still has plenty of restaurants and plenty of people going to restaurants.
Restaurants just need to raise their prices to cover the difference, and patrons make that back by not needing to tip.
It might not be as 'efficient' as having clients directly paying the wages of your staff, but it is more fair, transparent and reliable.