I went to a restaurant last month that automatically places a 20% tip on your receipt.
But if you pay by card like I do and don't read the fine print in the bottom of the menu front page like I do, you end up giving a 15% tip and then finding out about the 20% tip after you've accepted your food cost+ 15% on their stupid little tablet. And of course I'm not going to make a big deal about it. I'll just never come back.