Customers are encouraged to leave a tip once they are done with their meal if a waiter/waitress is involved. Tip should be about good 15% of your total bill but can be lower if you were not satisfied with your service.
What do you think about those restaurants that includes the 15% in your total bill? Shouldn't the tip be the customer's decision rather than the restaurant's decision? Good thing not all restaurants have agreed to such rule.
Maybe those who works as a waiter/waitress will disagree.