Twenty some years ago one of my first aviation jobs was flying tourists through the Grand Canyon from Las Vegas. After an exhilirating flight below the rim we would land at the Grand Canyon airport where they would continue with a bus tour and lunch at the south rim.
I remember an obnoxious bus driver coming up to our crew and thanking us for our flight. He then flashed a thick wad of bills, all tips, and said he was grateful for our "priming the pump" and putting the passengers in such a good mood. His tips were greater because of us.
We figured the bus drivers with tips were making about 4 times our salary.