I see them everywhere. The most insulting one was at sprinkles where I had to place order in the POS myself and the guy was just handing me a box from the shelf right behind him.
The most insulting one I've seen is at a self-serve convenience store in the Newark Airport. There is no staff that you ever interact with. Who does the tip go to? You for ringing yourself up?
I just got self-serve frozen yogurt yesterday, the only service interaction was the cashier telling me to put my cup on a scale and saying my total. What am I tipping for?