I live in Aurora, my wife has a daycare, one of her parents is an school teacher in Aurora Public Schools (APS) (will return to this point shortly).
To hopefully provide more solid information after reading all the above posts: when I attended APS in the 70's & 80's, school lunches were $1.35, I can't imagine that they went DOWN in price since then. A local news source is claiming that the child simply forgot her lunch money, and lunch lady felt bad for her.
Returning to my first point: this parent (known by my wife's customer), has done this quite a few times in the past. From what he claims, she does pay the money for the children as she has it. If at the time of providing a meal she does not have money on her, she will pay it later after she gets paid.
My personal opinion: I see nothing wrong with what she did, as a matter of fact, remembering what that food was like I think she may have harmed the child more than helped.