Aside from the baksheesh issue, I guess people who don't travel a lot in foreign countries should be aware that if you have an e-ticket, it's not easy in many foreign countries to just enter the airport and walk up to the check in desk without a showing a printed itinerary. You can do that in Western-type countries, but in the developing world, you should always carry hard copies of your itineraries that you may need to show at the airport entrance, the entrance to the check in area, etc.