Yeah let's take away the task of parenting...
Parents don't have much to do with what a child decides to buy at a school lunch.
In any case, these rules are fine, though I'm not surprised people are complaining. If you don't like what's being sold, many students can just bring their own lunch. I understand not all students can afford to do that, but school lunch was never exactly great to begin with. If your going to sell kids crap, might as well be healthy crap.
The law of product management: Cheap, fast, good. Pick 2.
Up until now, government schools always picked cheap and fast to save on money and effort. This mandate is for cheap and good, which involves more labor costs. In so many words, this is a mandate for a tax hike.
Really, the state of our cafeterias is deplorable. I work at the closest thing to a fine-dining restaurant my town can afford. My boss did his best to copy a 4-star restaurant menu and ambiance, repackaged it at a third the price, and while the menu is not quite that elaborate or complicated, he still basically succeeded. That's what private sector competition is all about.
My university cafeteria cooks what I would call "average" cafeteria food, but they charge $7 for the same buffet I could get for $4.50 at a local dive. They have no sense of competition.
Really want to give students better meals? Offer Subway a chance to cater food to the students on the taxpayers dime and have them compete with school cafeterias. You will see those cafeterias cooking some great, healthy food the next day.
You know what's funny about that suggestion? My high school actually DID that. It's how I was introduced to Subway. The food was better, but it was also several dollars more expensive and most of my fellow students didn't go for it. Only the ones who could afford it, like me, did. It didn't really encourage my cafeteria to suddenly try to find a better supplier and offer better food. Being private sector doesn't somehow mean something will offer something that is both better AND cheaper. If anything, including the private sector in something like this would just cost tax payers more, because unlike the public sector, the private sector will need to make a profit. They may offer better food, but they will also charge more.
My current university, FAU, also has both a food court with stuff like Wendy's and Quiznos, and a $7 University buffet. Food ranges from shit pizza to a pretty nice deli, and both places are generally pretty packed. Hell, the buffet gets more traffic, even though makes you bring cash because they don't take cards, adding inconvenience on top of the price. That private sector competiton doesn't really seem to mean much.