But restaurateurs, giddy at the prospect of passing labor costs directly to customers,

They don't already do this when they charge you? If they had to pay their servers more, wouldn't they need to charge more to make up for the difference?

Tipping does not incentivize hard work.

Maybe not when tips are pooled they don't. They sure incentivized me to work hard, and to develop a pleasing personality. I had a seriously teenager attitude problem when I was younger and working at grocery stores and whatnot, and had the classic "us vs. them" mentality when it came to customers. When I started delivering pizzas that changed. The harder I worked, the more personable I was, the more money I would bring in each night in tips. Not immediately, but imagine the surprise when you see someone actually requested you by name to deliver their food just because they felt that their food arrived faster when you did it, and enjoyed the short interaction enough.

The factors that correlate most strongly to tip size have virtually nothing to do with the quality of service. Credit card tips are larger than cash tips. Large parties with sizable bills leave disproportionately small tips. We tip servers more if they tell us their names, touch us on the arm, or draw smiley faces on our checks. Quality of service has a laughably small impact on tip size.

I would assume a server who takes care to do all those things is also taking care to provide a quality service. So in one side of the authors mouth they are saying that servers who go the extra mile get extra tips, and on the other side, they say servers who go the extra mile don't? Which is it?

Racism racism studies say this ethnic group tips less racism racism...

My personal experience was different classes of people tipped differently. Ironically, bigger houses typically tipped less. Drunk people either didn't tip at all, or in some cases, would tip multiple times, making up the difference for the non-tipping inebriated and then some. College students we're terrible tippers too. Doctors were probably the worst tippers of all. Ethnic group has little to do with it, but why let that get in the way of an opportunity to race bait?

IMO tipping is the best opportunity for someone in high school or college. It's one of the few options you have where you can get real-time feedback on the quality of your service. It's one of the few options where you can make beyond the minimum wage. If it weren't for overtime pay laws, it would be one of the only options someone had to get themselves out of a financial jam. I recall one week where I had put in too many hours, I was only focused on bringing home tips so that I could fix my car, but after 40 hours I was forced to go home. Imagine how frustrating it is to be killing it on a weekend and having to stop abruptly because the employer would have been legally obligated to pay you time and a half whether you wanted it or not.

Working for tips was a good experience for me and it was actually a natural stepping stone to eventually working freelance full time. When you experience the correlation of hard work to income, the transition is smoother than going from "paid no matter how hard you work" to not getting paid if you slack.