Do the math and figure out how much each passenger is paying you. Say you do a 1.5 block flight and your pay comes out to 40/hour for that flight, that means you made 60 for that flight. 70 seat RJ = 70 pax, each person paid you 85 cents. What a nice tip! Increase their fares by 85 cents and double my paycheck, why dont ya.
You're already getting "tipped." It's called your paycheck.