My guess is that there is no single mechanism, it's just degrees of freedom + capitalism. If you have a relatively unprocessed food, there's definitionally not

My guess is that there is no single mechanism, it's just degrees of freedom + capitalism. If you have a relatively unprocessed food, there's definitionally not that much you can do to it. Market forces dictate that food companies produce the cheapest possible food with the best taste. Evolutionarily, food that tasted good was good for you. Food science has developed, in the service of the market, to make good tasting food, especially food that tastes so good that you get addicted to it, that's made from cheap ingredients. Good for you is neutral unless the customer can detect that the food is not good for them. Generally, cheap ingredients are not as good for you. The ingredients are cheap because they don't taste good, and they don't taste good because they're not very nutritious. If you give food science and the market some rope, they have a bajillion ways to make cheap things that taste good.