I don't like the tipping concept, but I do tip - the same percentage everytime, regardless. In UK, 10-15%, in USA 20%
The problem with tipping is it reinforces a very clear power dynamic between eater and waiting staff. If a staff member is rude to me, I will complain. Otherwise, I want them to have a living wage. The problem in USA is it's balanced so that the only way to have a living wage while waiting is making sure you get your 20% every time, and/or never have to serve europeans who don't know about US wages.
Studies show that pay linked directly to performance actually hurts performance over the long term. Further reading "punished by rewards" by Alfie Kohn.
Mr Pink probably never waited tables, or struggled with money.