> For example — are cheeseburgers and French fries junk food? What about when you make them at home, or at a fancy restaurant without artificial ingredients? Is it certain additives? If McDonalds makes a happy meal without additives, is it no longer junk food?

Yes, this is all junk food. It's not that difficult.

Eaten in moderation these things are fine. But they are highly palatable calorie dense meals that are not great for you over time and in huge quantity. A burger is generally speaking a burger, regardless of how fancy. Deep fried stuff is deep fried, regardless of the cut of the vegetable or how organically it was grown.

Your latter question is far more interesting to me. I don't have a solution for that really. Society gets what society demands. I don't know how you'd fix those incentives without seriously horrible second and third order effects.