I can’t take a waiter/waitress seriously if their discussion includes the phrase “on a good night”. As a salaried employee who gets paid every other week, I have one “good night” (pay day) per pay period that’s probably better than any good night you will ever have as a waiter, but it just makes more sense to think about the longer term (how much I make per hour, or per week, or per month).
If you look at a long enough time horizon, your pay, even as a waiter, is probably fairly consistent. When I worked in pizza delivery my long term average was around $13 per hour after I paid for gas. There were certainly days on which I made more than my average, and the cost of those days was the days when I made less than average. Part of the compensation for working days in which I made less than average was that I got to work days in which I made more than average. It all boiled down to about $13 per hour.
Boil it down. Do the math. If you make $30 per hour for one shift out of 100 and you make $10 the other 99 shifts, that’s just barely over $10 per hour on average and you’re better off making $15. If you make $30 per hour for one shift out of 3 and make $15 the other 2 shifts, then you’re better off making tips. But I suspect that, by design, wait staff will get paid about the same in a post-tip world