Back in 1967, we were scheduled to fly from LHR to Oslo on BEA, and as our scheduled departure time came and went, an airline employee appeared, apologized for the expected two-hour delay, and led us into what may have been a lounge. There we found a buffet with sandwiches and tea.
Automatic food vouchers for delay seem to have disappeared some time in the early 1980s. I remember because my brother got stranded at ORD on his way to school in Cleveland, and as an impoverished student expecting no more than a couple of hours in the air, he had little money with him. He had to spend the night in the airport, and the small amount of money he had on him was not enough to buy anything substantial from the airport concessions. All he had were some Christmas cookies in his carryon.
We were all surprised that he didn't get a meal voucher, because that had been our experience previously.