Tipping is only considered rude in a handful of countries like Japan. It’s expected in Africa and the Middle East. Denmark and France add a tip to your bill for you. It’s not expected in most European countries, but most service workers, particularly in tourist areas, are fine with it.

Federal law in the U.S. only requires employers to pay tipped employees $2.13 per hour, but in some states, the minimum for tipped employees is much higher. In California, the minimum is $13 to $14, depending on the number of employees the business has.

So why do service workers put up with it? Because, in some cases, with tips, they might make as much as $20. The Federal minimum wage for non-tipped employees is $7.25 per hour, so it’s easy to see why servers would not want to be treated the same as other workers.