So here's what will happen: Poorer kids--you know, those same ones who tend to have lower test scores and less involved parents and more challenges to doing well in school--either won't come to your school in the first place or will quit because they're hungry. Your test scores don't get dragged down by those pesky poor kids!
And, even better, you don't have to mention this when you toot your own horn and say how much awesomer you are than traditional public schools.
I'd be unfair here if I didn't point out that California seems to be an exception rather than a rule with this policy, or that charters here in New York certainly do serve food (in fact, some of them serve very good food, which raises its own questions, but never mind that for a moment). Not all charters take this radical step of choosing not to provide meals.
But they could, at least in California.
I hope the ramifications are obvious.