> why does healthy food cost so much more than processed food?

It doesn't. Carbs like rice, potatoes, etc. are incredibly cheap. Protein like ground beef and basic cuts of chicken are not expensive. And broccoli, carrots, green peppers, apples -- these are not exactly breaking the bank. Product is seasonal, so you vary what you buy according to what is cheapest this week.

Meanwhile, stuff like breakfast cereal and potato chips and Oreo cookies actually are surprisingly expensive.