You can cure you from perfectionism and learn how to work fast and cut corners near 1 minute of your work
You can learn how to deal with a permanent lack of supply
You can learn how to deal with different cultures and languages (American is not presented)
You can learn how to work under huge pressure
You can learn how to keep your motivation in a zero-respect environment
You can train you to receive satisfaction from providing a customer services with just bare minimum pay and no tips at all
You can receive a free meal (if you like fast food)