Sick ones. See here. I seriously don't think this was a classic flim-flam, though it certainly had that side effect.

From the link above:
Several theories exist about a mother’s motivation to commit the abuse of MSBP [Munchausen syndrome by proxy]. She may believe that the ill child will bring a closer relationship with the spouse. More likely, though, is the idea that the mothers have had an emotionally deprived childhood with a high probability of a history of physical abuse. These women may feel insecure, uncertain, lonely, and depressed. MSBP may be a mechanism for expressing anger and fear; perpetrators are seeking emotional support, love, and nurturing in the context of disease and illness. Furthermore, the medical environment may allow the mother to escape some of the responsibilities of parenthood and the reality of unpleasant events in her life or provide her with the attention she seeks. When confronted with a sick, young child, the healthcare team will turn to the mother for a history, and in an effort to provide holistic care, she will be included in decisions and treatments. This inclusion and consultation regarding her child reinforces the mother’s need for attention and support. So every time the child is ill or brought in for treatment, unsuspecting nursing and medical personnel are meeting her dysfunctional psychological needs.

The mother ". . . said it started as a white lie that got out of control, was her explanation," [Urbana police officer Gary] Kimpel said on ABCNEWS' Good Morning America (from the article you linked to). If the mother was acting out in a classic Munchausen syndrome by proxy pattern, she was just getting started. Her source of attention was the community and her neighbors' fundraising efforts. Had she not been discovered, I'm willing to bet that the "symptoms" would have escalated. That little girl was lucky to escape with her life. Hats off to the school staff and their sharp eyes.

The dad says he was in the dark. This, too, is part of the profile:

When the mother is the perpetrator, the father is generally emotionally and/or physically isolated from her and the child; however, the family may be intact. The father is often unsupportive, professing to have no knowledge of the mother’s actions. He may rarely visit the child in the hospital and blame work responsibilities for this absence.

Please note that I'm not condoning or excusing the behavior of these parents. However, to look at something like this merely as a confidence racket is to miss a serious component that might need diagnosis and treatment, as well as punishment for its criminal components, to prevent its recurrence.

This pattern of child abuse is an identified mental illness. That means that enough people have exhibited it at a clinical level for it to have its own name. That's what I think is the scariest thing. How often does it go undetected because the parent doesn't become involved with fundraising and the subsequent accountability to outsiders?

More information on MSBP, other forms of child abuse, and child health issues can be found at the Resources page of The Zero, Andrew Vachss's official website.

Regards--
Mary Anne