First, food affects every part of your health and functioning (mood, concentration, energy, sleep). All very important things that should not be easily forgotten about in the haste to find the cheapest food possible. Hell, if most people were even half-way educated about real nutrition they would realize that what their really buying is nutritionally-worthless pseudo-food. Its toxic crap that only contains empty calories and no nutrients. Actually the money saved on cheap groceries is later spent on medical bills for the inevitable disease triggered by years of a nutrient-depleted diet. How people still don't know this after decades of nutritional research and exposure of industrial farming is beyond me! Theres a good reason the "food snobs" go out of their way to buy fresh, wholesome, and organic food due to the higher nutrient value that helps prevent illness.
A crappy diet makes for crappy functioning! (New slogan?)
Really I don't blame low-income people for their consumption of processed, low-quality food at all. I know that the Junkfood industries have been amazingly successful at promoting their crap pseudo-food as acceptable and even healthy. People grow up with this stuff. The government subsidizes it. The Industries get away with selling it. The medical establishment receives funding from the Junkfood companies so their bias. Many mainstream research has been paid for by the same companies that mass-produce low-quality crap leading to fraudulent studies (which happens in many other areas of so-called medical science). All of this leads to misinformation on the true value of a high nutrient diet that includes the foods nessecary to maintain health.
Its not a bargain when it destroys your health. Yes, you can get loaves of white bread free out of the local thrift store, but remember nothing is free in this world. It comes at the cost of your health, life, economy, or environment. Yes, theres a recession going on and I'm not rich either. But planning and budgeting can go a long way. Its really saddening for me to see how many people and groups in the mainstream don't know about the value of food as medicine and overall wellbeing.