I think workers in a fast food or sub shop type of restaurant are considered non tipped and are compensated as such. There is one sit down restaurant in my area that is now a no tip restaurant. The wait staff is salary and make like $20 an hour. The prices are adjusted accordingly, you can tip on top of that, if you like, but it is not expected. The idea is to give the workers a steady income so they stay on the job during a slow period. The restaurant business is up and down and people have bills to pay so by giving their workers a known income, they stay. I am not sure how it is working out but the establishment is still open and doing business.
I only tip at a sandwich/coffee shop I frequent. The food is very good, the ownership is local, they take good care of their customers and I have no problem throwing my change or a buck in the tip jar. It is all situational.
This is a result of income inequality. You can not make it on min wage anywhere any more. Social Security gets a COLA adjustment every year. Min wage rarely goes up. So when it gets a big jump some people are shocked and think the workers do not deserve it. I think, if you step back and look objectively and fairly, they deserve the increase a social security recipient gets.