Passage 21
"Tipping" is handled very differently in the UK and America.
In the UK, the reason for tipping is to show that you really liked the service.
In the UK people have a high minimum wage, and no one can be paid below this amount for any work, so when you tip, it is mainly showing politeness to the service person, and to acknowledge that they did an excellent job.
The average tip is around 10-20%.
If you didn‘t like the service, you can always refuse to pay.
Or if you are a student or a traveler on a budget, it‘s OK not to spend the extra money.
In the US, you will often hear "tips" called "service charges".
It is essential to tip in the US, because the waitresses and bar staff are paid a low wage which they cannot afford to live on, and therefore your tip is much needed by them.
The business and the servers all expect that a tip will be given.
It‘s considered to be part of their salary.
In some restaurants, the tip wiil be added to the bill, so it‘s not optional.
The expected amount of a tip is usually 15%.
Of course, if the server did a really good job, you can always give them more.
原文：https://www.cnblogs.com/kamisamalz/p/13344069.html