Schools should be a safe place for children, if that involves taking care of their physical health in some small part by providing lunches than so be it.
It's a lot less damaging to society as a whole to provide healthy lunches for students than for children to go hungry, because there are so many consequences that stem from malnutrition for children, and youth for that matter.
Most parents will try their best, but kids still won't always go to school with much, that was my personal scenario, I ate a good number of those brown bag lunches throughout the 90's and early 2000's.
Some parents can't be trusted to manage money unfortunately, someone else spoke to funds being allocated to bills such as rent and the like, it's hard out there.
Implement a meal program and you know there are food options available for needy children, this will help both the children themselves and ease some of the burden for lower income parents, or parents whose income in spread amongst multiple children (because sometimes it ain't that someone is low income, it's that dollars have to stretch further).
It's hard to focus when you're hungry, it's harder to learn when you're hungry.
Physical health is so important for children, and what goes into the mouth, and what happens with the mouth is so important. This is part of why I'm excited about a dental program being implemented, oral health affects most facets of one's overall physical health, children and lower income individuals being able to access dental care is so, so important.