It's "cheap" if your labor is valued. I imagine the relationship between health consequences and income could somewhat be related to having multiple jobs, long hours, and being too tired to prioritize health after a long day.

That fast food looks quick, convenient and affordable when you're going from one job to another and don't have much time or the additional money to spend on healthier fast casual eating options.

I do not disagree that whole fruits and vegetables are, by and large, cheap and ubiquitous. If the health outcomes were tied to "cheap and ubiquitous" produce, we'd be off the charts. Yet, here we are.

My point is workers who are barely scraping by are disadvantaged to not have the flexibility that higher-income earners do, to actually have the time/energy to cook a healthy meal. Or pay someone else to do it. They end up opting for meals that don't offer the macronutrient composition they need (e.g., frequently the issue is overconsumption of carbs), and are lacking in micronutrients as well (because there aren't enough fruit/vegetable servings in their diet).