Not sure if this is the correct forum for Duty Free...Before boarding a USAirways flight from PHX to Mexico City and went to the duty free store inside Terminal 4, and bought a carton of smokes. After showing the cashier my boarding pass and passport, I was surprised I was handed the carton of cigarettes. In the past, they used to hard it to you just prior to boarding the aircraft (on the jetway).

What prevents someone from buying duty free at the airport, then just leaving the airport and dropping it off in your car in the parking lot, then going back through security again to board your plane?