Agreeing with Berenger is like agreeing with Ted Cruz, but here I am, agreeing with Berenger.
I am working class. We spend about $700 on food per month for two people. This is choice, half of it is in luxury foods I don't need.
Yet, consider the price of a bunch of fresh Kale (keep in mind that if you want to fill yourself in a healthy manner, one bunch of kale is enough for two days if that's your primary vegetable) or Spinach and how much it costs: for the same price you can get yourself a value meal burger and small fries.
Look at that choice. On one side, you have a product that is designed to appeal. Fat, salt, and sugar in the right ratio- a ratio that tricks your body into thinking it didn't get as many calories as it actually did. On the other side you have a bitter green that will not satisfy you. Not by itself. A green that you will need to take time out of your day to properly prepare for consumption. You could eat it raw. I don't usually (eh, maybe baby spinach is fine raw, but again, I was raised with a very different palate) find this enjoyable, and I sincerely doubt your average entry-level unskilled worker who makes $12k a year does, either.
However, I have been a student and probably will be one again shortly, so concerning myself with the price of food is something that was once routine.
Are rice and beans better nutritionally, than a value menu burger and fries? Sure, but that doesn't mean it's adequate. Which is why you look for canned vegetables, which become a little bit more affordable that fresh vegetables. Cheap eggs are great value, too. A standard, decent cheap meal is egg whites or white fish with beans and vegetables. You can go cheaper and less balanced with white rice and lentils or black-eyed peas.
So, yes, you can spend less money and get something more healthy than McDonald's, but what about frozen chicken nuggets and fries from Walmart? Or those little pocket pizza things? THEN you're spending even less for shitty food.
Either way, healthy food takes time and knowledge to prepare. Skill to make it taste decent. Instead of taking this time (at least half an hour) out of your day to prepare decent food that is still relatively bland, where you spent 12 hrs working at some shit job with some idiot bosses and similarly ignorant coworkers talking about nothing but what Niki Minaj's ass looks like this month, you could opt for a very convenient choice (active prep time for frozen nuggets? probably one minute) that has a superior ratio of fat, salt, and sugar.
This morning I could have taken the time brew my own coffee. In this case, it is actually superior in taste and mouthfeel to any over-the-counter franchise variant. Instead, I bought some shitty, saccharine iced coffee because I didn't want to take the time to clean out my french press, grind some beans, pull ice out of the silicon mold, and pay attention to the timer on my phone.
Imagine how much harder it is for someone who is not as (I am a better cook than most professional cooks; I imagine it would be hard to pick up a skill like that in a household that could not afford culinary variety) privileged as I am, or has not had as much exposure to deliberately chosen inconvenience, especially when the home made variant doesn't release as much dopamine as the commercially available choice.
I made this choice for convenience, and it is in the name of this fell god that we sacrifice ourselves. Every. Day.
God Bless America.
Edit: Sweat, I go to work with this guy who's fairly cut, and does cardio about once a week. He exists on a diet of redbull, candy, bacon, and dominos pizza. Still outsprints and outlifts the rest of us. Still outruns us in anything less than a 3 miler. On the other hand, there's a guy who eats about 1500 calories a day and works out twice a day. Still fat looking, and gets tired after about two and a half miles.
