Well, I have written on this, but as relates to Christians, and I will not go into all that here, but everyone should tip appropriately. I am sure they know, but are choosing not to in order to keep that 20 percent for themselves, or have never worked as a server. Then, I am sure they would have a different perspective. We can't control what other people do or do not do, that is for sure. I guess, just pointing out to your friends that the server is doing his job and it is the right thing to do, as there are plenty of other things going on behind the scenes I am sure that no one even sees, besides them bringing your food to the table.