The idea is sound-healthy, nutritious, chemical free foods for growing children. If there is a finer ideal I do not know of it.
Unfortunately, the reality of the situation has everything to do with economics and ignorance and next to nothing to do with the food. Budgets are being slashed in school departments, and food programs often are the first targets. Years ago there was much hooplah about ketchup being listed as a vegetable.
Politics and school lunch programs just don't blend in a manner conducive to the health needs of the students.
I ran across an article recently...
Under the 2008 farm bill, the District received $1.2 million this school year to serve students a vegetable or piece of fruit outside of breakfast and lunch hours. The program is likely to expand to more schools next year as funding increases to $1.7 million.
To see what the beancounters and bureaucrats came up with as a fresh snack, you gotta
read the article.