I appreciate you have some first hand experience here, but this is a very HN-style axiomatic argument --- "restaurants must have issues with meat going bad that ordinary people don't, ergo their meat must somehow be mummified with preservatives". Isn't it in fact the case that fast food restaurants have, relative to supermarket consumers as an entire cohort, extremely high and predictable turnover?

A neighborhood sushi place has an even bigger problem with spoilage than a friend chicken shack, but, for pretty intuitive reasons (I think?), I'd trust any well established sushi place with ahi and salmon than I would my own fridge.

Further: while fast food input costs are the highest single line item in their cost breakdowns, they don't come close to dominating, and labor plus rent dwarfs inputs even before you factor in franchise fees, marketing, and other expenses.