to your point, not exactly a one-to-one, but several discount airlines (e.g., RyanAir, PLAY, Allegiant, Frontier, Spirit, Wizz, Flair, AirAsia) already require an app to check in for a flight, or pay a fee. No app (or the horrors, no mobile), it cannot be done on a regular computer, must go to a ticket counter and pay a fee.