How are they measuring the costs here? Even fast-food burgers have significantly shot up in price.

If we go by raw ingredients, then healthy food can be considerably cheaper than pre-made garbage and fast food.

If we add the time cost of traveling to a grocery store, shopping, and then preparing the healthier food, then it could become more expensive.
Some of those time costs can be reduced with grocery deliveries however. This might not be a viable option in all areas though.

Then there is the fact that there are a lot of food deserts , especially in low-income areas.

Not sure where I'm going with my train of thought here...