I (respectfully) disagree. I think it's more of a social issue. It takes a lot more to process junk than to harvest whole foods.
Sugar is addictive, and they know it. They make it affordable, because they know you'll keep buying it. It's also supply and demand. Healthy foods are WAY more expensive in lower-income neighborhoods where people may not have been educated on healthy eating- if they're avaliable at all. So maybe even if I wanted healthy foods, who wants to ride a bus way out of the way to get to affordable veggies.
I'm not implying that the OP may live in a lower income neighborhood. Please don't take it that way. I'm just passionate about ALL communities having access to healthy foods.