In the last yr, I have been on buses, trains, ferrys, vans, limos, and yes, camels around the world. 9 out of 10 modes of transportation have a tip jar on them and a crew member holding a hat out when you get off it. Why can't we? I know it won't raise my pay $25k/yr but it'll buy the beer that night. Think about it, besides wal-mart and most other retail establishment, where DON'T you see a tip jar these days? You tip the cab/van driver on the way to the airport, the skycap, starbucks girl/waitress at the airport, why not the most important person on that trip, the pilot(s) that get you there?
There have been alot of good points brought up here, none is THE answer, rather many of them grouped together are a better answer to the problems we have today.