Buying drinks/snacks on planes in the U.S. It's not universal, but probably 50% of the domestic flights I take specify that they only accept debit/credit cards for payment. On a recent flight that did accept cash, I overheard a passenger ask why this flight took cash and others did not, and the flight attendant said that their particular plane hadn't been fitted with some system that would allow credit card checks in flight, but it was on their maintenance schedule.