Yep - been proven time and time again.
I had a bartender friend back in the late 80’s that just killed it at a very popular restaurant w/ a big round bar in North Palm. She could take home $500-$600/night on a Friday or Saturday.
I swear I remember her telling me that occasionally she’d get a “negative paycheck”. The restaurant was probably only reporting a fraction of her tips, but still some weeks it got too much? Was there such a thing?