This is fascinating!
What do we know about tipping?

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

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

– Tips are higher in sunny weather.

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