Even when I use the meal vouchers at an airport food venue, they never type in the card info on the voucher directly into the register. They take the amount off, have me pay the rest, and then staple the receipt to it for later processing.

Ironically back in the day when it still existed, I encountered an airport hotel (Wyndham Garden EWR, it no longer exists) that was what I would describe as a meal voucher mill. The front desk and the onsite bistro had signs on the desk and all over the windows and doors indicating that they accept all airline meal vouchers and "cargo vouchers" with a hand drawn cargo ship on the sign (which I admit, I'm not sure what those are! Perhaps they're issued to cargo ship crew?)