I've always disliked the perception that poor people necessarily eat poorly. Rice, wheat, barley, oats, beans, and root vegetables are grown in abundance in developed countries and so are inexpensive; they do not spoil quickly; and are very healthy. Most vegetables will keep for weeks in a refrigerator and months in a freezer. Sardines (fresh) and eggs provide much better protein than meat.

I think the cost of "healthy food" is mostly rooted in ignorance and a taste for simple sugars:

"For a Brit, there can be no greater comfort food than a custard cream."

There's your problem.