European low-cost carriers take reducing operating costs to a whole new level, and they often do so in ways that one could never even anticipate. Anyone who has ever flown Ryanair is used to being bombarded with product advertising, invited to pay for additional services of all kinds, and even offered package deals to combine flights with airport transfers. However, these are all ways that the airline will generate extra revenue from you as the passenger, and they are not the principal reason why these airlines are allowed to offer such unbelievably low fares.