Americans eat so much processed food simply because it is much cheaper than fresh food. Processed food is made to get consumers addicted (through convenience, taste, etc.) and encourage them to consume much more. Fresh food is almost the opposite.
I grew up in a country where freshly made food is actually cheaper than processed food, even to this day. People who stick to a traditional diet are mostly thin, while those who stick to a processed food diet gain a lot of weight.
I don't understand how people come to this conclusion
Beans/grains/legumes are cheap
Frozen veg is dirt cheap (and retains its nutrition as good as, or better than fresh). In-season fruit and veg
Which foods are more expensive?
People are door-dashing their salaries away and complaining about the price of fresh food...
Convenience and addiction makes more sense, certainly not price
In general the American diet is very meat-based. Once you hold meat as constant, you realize that fast-food or ultraprocessed food are the cheapest way to get a meat-based meal. E.g. McDonald's is probably the cheapest way to buy a hot meal containing beef (and it used to be even cheaper, you could add fries+coke for just 50c in the past). A lot of poor Americans eat hotdog sausages, microwave meals etc just to get some kind of meat even if it's low quality.
Are you sure? Let's take the example of the McDonald's Big Mac which is $6.72 [0]
The between the 2 patties, the sandwich contains 25g of protein (not grass fed beef) per sandwich. It's fair to assume the majority of the cost of the ingredients of a burger is the meat. The rest is pretty cheap because you only need a small quantity of it to complete the meal.
Here are prices of Costco grass fed beef patties: [1]
15 patties for $36.31 Each patty contains 26 grams of protein, which is more protein than both patties of the Big Mac combined.
cost per patty = $36.31/15 = $2.42
cost of Big Mac = $6.72
That doesn't even come close to the majority of the cost of the Big Mac. I could do a full analysis of each ingredient, but I think it's clear from this data that fast food is not significantly cheaper, especially considering that the Costco patties are higher quality.
Edit: formatting, and also burgers are super fast and easy to cook at home.
[0] https://www.mac-menus.com/big-mac/ [1] https://sameday.costco.com/store/costco/products/20021199-ki...