I don't think food has gotten that much cheaper in the last 50 years. Don't believe the fake CPI. Just take the average hourly earnings and divide it by something like the big mac index or a basket of food commodities.
In the 35 years since 1988:
- dairy has gotten 20% cheaper in terms of wages
- bakery/cereal products have stayed roughly flat vs wages (cheaper since the 90s but more expensive since the 70s)
- fruit/veg products have gotten 5% cheaper in terms of wages (though the same level as in the late 70s/early 80s)
- rice/pasta/cornmeal has gotten 15% cheaper in terms of wages
Caveat: Over time frames this long, average hourly wages don't mean like for like hourly wages for the same job... the number of low-paid "deliveroo driver/amazon delivery guy" low paid part time jobs has increased, pushing averages down. (I.e. things have gotten more expensive as measured by minimum wages, but things have gotten much cheaper as measured by the wages of a skilled professional.)
I'm assuming in most countries also, subsidies, formal/official cartels, price controls and other policy instruments would make it very hard to compare apples to apples.