Not on a “per calorie” basis they aren’t. And I’m not really sure by what other metric you can compare them. But look at how many calories of broccoli $3 gets you compared to potato chips. Then you have to add in the time of preparation.
Additionally, many impoverished people tend to live in “food deserts”, areas without grocery stores, but many fast Food locations.
The deck is definitely stacked against the impoverished.