If you're shopping at Whole Foods, eating healthy will cost an arm and a leg. If you're shopping at a normal supermarket, eating healthy doesn't need to be expensive. You can buy enough green beans and red potatoes for a large meal for the cost of a bag of frozen fries. Those people you see with shopping carts loaded with food also most likely go out for dinner at least twice a week, and probably don't bring leftovers to work for lunch. The average American
wastes an enormous amount of food.
There's also the long-term ramifications of eating garbage. Sure, maybe you save $10/week by eating fast food every day, but you will be paying for it with health issues years down the road. Compound this by people being lazy and never going to the gym, and you're completely screwing your future self.
I buy only fresh fruits and vegetables (this includes green leaf lettuce, which actually has some nutritional value), chicken, pork, eggs, milk, yogurt, and bread if I need it. I usually have red meat on the weekends. There's also butter, oil, and all the other smaller stuff like nuts, chips, deli cheese, and ice cream, but I only need to buy those maybe every few weeks or once a month. My weekly grocery bill is usually around $40-60, depending on what I have in stock, without using coupons.
My breakfast three times a week is steel-cut oatmeal with some honey, blueberries, banana slices, and a handful of walnuts. The cost of this is cheaper than any breakfast sandwich you might get at DD and orders of magnitude more healthy. The other two days I have an English muffin with a slice of cheese and an egg, also with a handful of walnuts. Ditto on being healthy.
Cooking, if you know what you're doing, is easy. The problem is most people are just lazy and have no idea how to prep efficiently. It shouldn't take more than an hour to cook a full, healthy meal, with a main dish and two sides, cleaning as you go. I like to plan my meals so that I only spend maybe 30 minutes cooking on a weeknight, and I always have leftovers for lunch (though I don't have for lunch what I had the night before - I rotate a bit).
As purbeast said, grilling is even easier. You have what, a couple of dishes you can throw in the dishwasher? I brush the grates immediately after cooking and it only takes about 20 seconds. I can cook a full pork tenderloin with asaparagus and mashed or grilled potatoes in 30 minutes - most of that time is spent waiting for the grill to heat up and letting the tenderloin cook/rest, and I make enough for three meals. Total cost is less than $10, or $3.33/meal.
I'm a single guy who is at work 11 hours each day (one of those hours is spent in the gym) and lives alone in a house. I tend to sit down for dinner, whether it's leftovers or something I just cooked, by 7:10p.m. every night. I guess having kids would make it more difficult, but if you're married there's no excuse.