Those eating habits are taught from young and when you can buy food on your own, the money will be spent in these places. Unfortunately they may get to a point when they have health probs and then have to taper off of this or realize Im spending 8-9 dollars on a fastfood meal, I can pay the same thing and get better food at a restaurant. But lets be real....you have 20 bucks in your pocket, might need gas and food....the dollar menu becomes a reality at that point
semi on topic
Comparing apples to apples in terms of so called "wealth, economic class, etc" in one area of the big picture
Inner city areas are filled with fast food spots, cant say it isn't the same for trailer park filled areas Ive seen, but rural areas where many poor whites may live live arent filled with these places because it doesn't pay to put them there. The more rural areas may have mom and pop spots that may be cheap but serve more wholesome food than a McDonalds etc.