I don't know whether your scenario is real or imaginary. My sister has been a case worker in child-protection for the last five years and she has never run accross anything like this. Yes, I do know that sometimes the child-protection people step in for the wrong reason, at the wrong time, etc., but 99.99% of the time, it is to intervene in situations that would make your hair stand on end. Note that even in your example, what is hurting the single mom is not the child protection agency, but her lack of money and status.
Joanna B