I do not believe the top answer adequately explains tipping in America. "TIPS" means To Insure Prompt Service and the amount to TIP is done by a percentage. The reason for this is... If you are eating at a nicer restaurant then the server has more responsibility for example knowing the menu by heart or being able to speak about wines or alcohol in general. When one has a skill (like being able to provide a lovely dining experience) they should be paid accordingly. Now if you are at just a simple diner then the cost of food is cheaper and therefore the server is not expected to do as much.

The structure of restaurants is that servers are paid roughly $2.15 per hour by the restaurant and the servers TIPS should make up the difference to equal whatever the minimum wage is in that particular state.

Now you may say the restaurant should just pay the servers a living wage, right? Well in order to do that the restaurant would have to raise the cost per meal and with all of the options no restaurant would be able to survive.

Servers perform a service like any blue collar job but are not treated as such.

That's America.