As soon as I began reading this thread, I was thinking about Jamie Oliver's campaign also.
It does vary though, depending on how meals are organised in schools in your country. I gather in England, and also in the US, there is a common practice of kids being fed at school in the cafeteria. In Australia our kids can get fed, but the school cafeteria is more a counter and nothing else - the kids buy their lunch from a range of available foods, then take it outside to eat it.
What Jamie Oliver was doing, was on multiple levels. First, he worked to make sure the school canteen had only healthy options available; but also staying within the budget. He then worked on the kids themselves, to make sure they understood about healthy eating. One really effective way to do this in Australia especially, has been to include gardening, cooking and other related topics, into the school curriculum. So the kids themselves grow the food, they are involved in it, they learn about what they are doing and then they get to harvest the food and learn how to cook it. When they have some ownership in it, it's amazing what the kids will happily eat. If they've grown it themselves, they'll even eat broccoli and brussels sprouts.
There's nothing in Jamie Oliver's programs that dictates what parents can or can't do. What it does, though, is make sure of several things:
1) The schools and school staff have to ensure that the kids are only given access to healthy choices, because they have a duty of care which they violate if they do not ensure that the kids are looked after in this way.
2) The kids themselves are taught about healthy choices and encouraged to make these choices a part of their lifestyle; families can be brought in to learn also, and given useful information about how to eat well AND do it without it costing any more.
3) Kids are taught hands-on how to recognise the food as well as how to prepare it so they actually like eating it.
One of the really sad things about the British program when I watched it, was the number of kids who didn't recognise the raw vegetables Jamie showed them. It wasn't obscure stuff, either. He also taught them about herbs and other flavourings as well as how to use them. There was a lot of resistance to begin with, especially form the boss of the school canteen who was very determined that this little Cockney upstart wasn't going to make HER budge on anything! She was determined to keep feeding those kids the pre-packaged fried potato stuff laden with additives and rubbish, as well as fish fingers (also laden with rubbish) and chicken nuggets (have you seen what goes into those things?). So he had to prove to her that he could come in under budget AND prepare food that was easy, as well as acceptable to the kids.
At first the kids wouldn't touch food they didn't recognise, but once Jamie taught them about where the food comes from and involved them in preparation, these kids really changed.
The thing is, kids learn what they're used to. And what they get given every day is what they get used to. Plus, school canteens do what is easy and cheap. If they really don't care about nutrition, considering it's the parent's job to make sure the kids eat right while they're at home and what they have at school doesn't matter, it can actually perpetuate the problems and make it more difficult for families who do try to feed the kids right. So this sort of issue has to be handled on a wide front, if there is going to be success.
In Australia, we now have strict rules about what schools are permitted to have on the premises, in terms of food choices. It's not law, but it IS Dept of Ed regulations. There is still a lot of room for improvement.
We do have an increasing number of schools that are following the Jamie Oliver model, where the kids grow the food, they harvest it, they cook it and then it is sold in the school canteen. And the canteen can still turn a profit, as well as ensure that healthy choices are there.
When the food is really fresh and you know where it has been grown, it is also doing a lot of good for the environment because the food hasn't been picked for days or possible months, plus it hasn't been trucked half way around the planet before being consumed. Eating local food means no greenhouse debt due to the travel cost.
It's win-win-win in so many ways.
If you can do some digging on Jamie Oliver and what he does, you might find it very interesting. I did.
http://www.jamieoliver.com/jamies-ministry-of-food/
Marg