There's free and reduced price lunch in Georgia too. It's a federal program, so I bet every state has got it.
http://www.fns.usda.gov/cnd/Governan...lityManual.pdf
I don't think it requires much supporting documentation to qualify.
Some parents who owe may have recently fallen on hard times, but some people are deadbeats and choose not to pay for things they could pay for, particularly when they learn nothing happens when they don't.
Other parents could chip in to cover them, or the parents who haven't paid could make paying to feed their own children a higher priority, either with cash or by doing the paperwork to document that they truly can't afford to.
Just racking up charges isn't the answer, but they were probably kind of taught in previous years, by the district's failure to aggressively pursue the debt, that they didn't have to. Now they do.