> Junk food is only cheaper than healthy food because our society has made that choice, and it can just as easily choose to change that.
Junk food is cheaper because it's easier to make junk food. If you want to make food more palatable cheaply, make it denser, fattier, and sweeter. i.e. turn it into junk food.
You could check https://en.m.wikipedia.org/wiki/Sugary_drink_tax as a starting point. From a skim it doesn't look to me like a small tax is some kind of miracle cure for anything in this regard. Though I don't think anyone claimed that it would be the one factor that fixes everything. There is no one factor, and having the tax as part of a toolbox seems reasonable.
I don't this is really true? Candy is expensive. Chicken thighs, certain cuts of pork are affordable. Along with rice and filling sides like beans. You can eat well and cheap.
It might only be cheap if you're talking about time too?
There was a study that determined that the reason for the sugar+fat combo was that sugar "scratched" arteries and made them easier for fat to stick to.
Just plain fat is OK, because it doesn't stick to healthy arteries. But combine (highly processed) sugar and fat, then you get an insulin spike AND the fat clogs your arteries more easily.
Most of the research is that it's both. (Tt's the worst when fat and sugar are together) Specifically food is more rewarding, denser, cheaper, and easier to find than it used to be, so we overeat it. Same thing happens with almost any animal that's given ad libitum access to the american diet.
It seems there are two societal solutions, extremely heavy handed government interventions to ban tasty food or we invent a weight loss pill.