When I was in high school I worked at a car wash that had a very prominent “No Tipping” sign. Tons of customers slid us tips.
One day management took down the sign and the tips dried up. Why?
We thought it was people trying to pull a fast one. Beat the system.
Anyway, about two hours into the shift we realized the tips had dried up and we threatened to quit if management didn’t put the sign back up by lunch time. The sign was back up within the hour and the tips started flowing.
I’ll bet the wait staff at this restaurant is cleaning up on tips as well.
What good is a tip jar if no one sees you put money in it? :-)