What do we know about tipping?

1. Two studies show little relationship between quality of waiter service and size of tip.

2. Hotel bellboys can double the size of their tips, on average, by showing guests how the TV and air conditioning work.

3. Tipping is less prevalent in countries where unease about inequality is especially strong.

4. The more a culture values status and prestige, the more likely that culture will use tipping to reward service.

5. Tips are higher in sunny weather.

6. Servers can increase their tips by giving their names to customers, squatting next to tables, touching their customers, and giving their customers after-dinner mints. (query: how do lap dances fit into this equation?)

7. Drawing a smiley face on the check increases a waitress's tips by 18 percent but decreases a waiter's tips by 9 percent.

8. In one study, waitresses increased their tips by 17 percent by wearing flowers in their hair.  In general it pays to look distinctive albeit not freaky.

Here is the link.  Some of the information draws on studies by Michael Lynn of Cornell.  Here is his home page.  Here is his page on tipping.  Here is his advice on how to increase your tips; he asks that you tip him for it.  Here are his dogs.

My questions: Is tipping any harder to explain than why we don't just leave the restaurant without paying?  Given that (almost) everybody tips, is the final incidence more or less neutral for the customers?  Do we tip, in part, to produce the illusion of control over how we are treated?