What consumers rarely notice, however, is that loyalty reward programs, such as airlines’ frequent-flier plans, are a lock-in in disguise. True, you don’t pay an early-termination fee when you abandon your longtime airline to take a more convenient and cheaper flight with Spirit Airlines Inc. But there is an implicit penalty -- what economists call an alternative cost -- in the form of reduced rewards.

Loyalty rewards lock consumers in just as effectively as termination penalties. A $250 penalty creates the same loyalty incentive as a forgone $250 reward. A rational consumer would recognize that both programs penalize her for being unfaithful: The wireless company will charge a $250 fee; the airline will deny a $250 reward.