Schools are in many ways just reflections of a society and its values. Schools don't exist in a vacuum, so comparing American schools to Finnish schools can not be done as an apples to apples comparison.
I've worked with inner city youths, and that is completely false. If that were true, we'd expect a very skinny poor population. Instead, a large percentage of America's poor are overweight.
I think the real reason is that food generally costs a lot less than it used to cost, relative to housing and other expenses.
Poor people often know how to cook, out of necessity, and make the food taste better by retaining more of the fat, adding carbs like rice, and plenty of meat.
Food is sustenance, culture, entertainment, and reward all in one experience. And the price is relatively low. If you have $10, you can dine very well if you can cook.
[NB Genuinely interested - not being snarky]
Anyways, we'll just have to wait and see whether co-operation is more effective than competition. For now, it seems like competition is winning, but the question is at what price.
It's just a society that has spent decades in the thrall of a bloody-stupid ideology, to the point that America is only now recovering the vocabulary to talk about its problems clearly.