My thoughts as a ramp rat at an FBO.
The big tippers should be the passengers not the pilots. When I unload 8 golf bags, 8 HUGE hard-sided suitcases that weight 30+ lbs, and other small bags and load them into 2 full size cars and I begin to worry about having a hernia. They don't tip. They just arrived in a CL60, GV, or F900 but just go on. What happens next time they come though is I might get to them a little bit slower or just take my time.
When I get a tip from a pilot they usually find themselves fueled a little quicker, there pax handled a little quicker, fees for GPUs or other various services sometimes get dropped.
With me how does a pilot get away with not tipping but with a faster fueling or with more helping to them? A GOOD ATTITUDE. Just because I pump fuel doesn't mean I am not a human being!!!!
With me...have a good attitude, talk to me, shoot the s#*t with me, thank me and I will thank you.
One final note. We have a jet that comes in about once a month. The pilots never tip but are always as nice and cool as they can be with us. In my opinion they get VERY good service, all because of a good attitude and because they buy a ton of FUEL!