America is synonymous with a peculiar list of cultural exports: Coca-Cola, Bruce Springsteen, peanut butter on everything, monster trucks, prescription drug commercials with terrifying side effects, and, of course, tipping.I remember the first time I visited the United States, some 16 years ago, shortly after finishing high school. Coming from a country where leaving a few spare coins on the table was considered high praise, the whole business f…