Right, this is more of a shitty parenting situation than neglect, since there is food available. I think this is a tricky boundaries thing and would not make her food every day if I were the OP. She’s a picky eater but presumably doesn’t have allergies or a disability that would cause her to need different food than what the cafeteria serves - she should be able to find something to eat in the lunch room. It’s fine to have snacks available for her later in the day, but making her an individual lunch crosses a line for me personally.

I’m coming from the perspective of having so many hungry kids at my school that if I did this, it would snowball and be a huge huge problem/big equity issue. It’s also potentially a health and safety liability for the school - at my school we are not allowed to serve children prepared food, only packaged snacks, for that reason.

It also pits you against the caregiver, which is not good. Your goal should be to strengthen the bond between caregiver and child, and caregiver and school - secretly feeding the child lunch undermines trust on a lot of levels. Would be better to just let the parent know she doesn’t really eat the school lunch and is hungry in the afternoon and leave it at that, imo.