A few years ago I wrote here about the unexpected symbiosis between economy passengers and business travellers on commercial flights. Largely unnoticed by people in either cabin, those buying each class of air ticket are unintentionally helping out their fellow travellers at the other end of the plane. Precisely because the two classes of passenger have wildly different priorities (the people at the front are sensitive to time, productivity and comfort; the people at the back are more sensitive to price), it benefits both groups to share the same aircraft.