As a disclaimer, I should say I have 2 elementary school kids. I try to educate myself on food and nutrition. I cook at home, and talk to my kids about exercise and health. Thankfully, we are all healthy and active.
However, this weight "dilemma" is societal as well. The kids spend more time in school NOT having PE, and parents spend more time at work. So even after school, kids go to some sort of afternoon care or an extra curricular activity until a parent can go pick them up at 6pm when they get off work. Leaving less time for the parent to be an active part of the child's development.
Let's also be realistic about cost. Good, healthy food is a privilege in this country - not a right. You can get a double cheeseburger for $2, but a salad will cost at least $7. We on this forum are privileged enough to be able to spend a sizable amount of money on a luxury car (no matter how entry level the 3-series may be
). So we have the privilege to be able to afford some of these foods. But what about people whose weekly food budget is $50? they can't afford too many $7 salads.
Why do schools allow these kinds of food? Because they're cheap.
Billup, I can tell you that when your kids are out of sight, you have no control. Yes, you can pack them a healthy lunch, but you're not there to stop them trading their lunch for a pokemon card, or a bag of potato chips. Yes, eventually you teach them not to do those things, but they will do stuff like that.
I can write about this forever, but lastly, I want to say that simply, not everyone makes food and health a priority. Not everyone is educated about it. And it isn't easy when Atkins is the way to go today and paleo is tomorrow's definition of health. Low fat, no carbs, whole wheat... no medical professional can come to an agreement. Again, some people take the interest to learn. others don't.