Do you know something we don't? How do we know the mother wasn't dead/in prison etc?
Are there other articles that explain this or have you assumed?
None of the various articles I have read on this have suggested anything other than a mother who simply didn't care that she hadn't heard anything about her 2 year old for days. Most semi-reasonable parents would be climbing up the walls if they didn't hear from their 2 year olds care giver for a few days. Let alone a few weeks.
I'm sure more information will come out about this as the tabloids dig into it.