[iron81]

I think that this is merely because the ballerness of El D and his friends has increased over the years. They have more money to throw around, they eat in nicer restaurants and so their tipping level has increased. I'm sure there are plenty of stingy tippers still out there.

I doubt that Diablo has his finger on the pulse of the actual staff as to what they expect from their customers. The "expected" tip is calculated from 1. His friends and 2. 2+2. His friends like to keep up appearances and cheap 2+2ers don't like to be flamed.