While their is some truth to what you say, DCS caseworkers are caught in a catch 22. If they are aggressive in taking children out of accused but not proven abusive environments they are gooberment nazis taking children from loving parents on flimsy accusations. If they wait for more proof or for cases to work through courts first and something happens, they're obviously idiots. But then they do work for big government, and we all know they're stupid, right?
The "beauty" of the CPS system is that workers do not need to wait for proven abuse to take kids out of their home. They do need to show a preponderance f evidence that the child is "in danger" of either abuse or neglect. It is the keeping of kids from their homes that needs "proof". In the meantime, they can petition the juvenile court for orders to make the parents attend classes in everything from parenting skills like when and how to change diapers to gaining "job skills" and seeking work, as well as the ever-popular anger management. They can also provide, through contracts, things like maid service to clean up a home that is beyond the capability of the parent(s), or pay for medical and mental health services for the kids and/or parents. All that is in order to abide by a federal law that mandated reunification of the family as the primary goal - which could also include services top prevent the "necessity" of removing the children even temporarily.
The major stumbling block to all of this is that, usually rightly so, the gooberment and its minions must rely on other family members, friends, or the schools to observe and report suspected abuse or neglect. Those are the folks that, in spite of anononimity and shield laws, are reluctant if not downright afraid to say anything until there is absolute proof. A lot of that does come from the heavyhandedness of the CPS system which has created its own Catch 22.
The other thing is tyhat there is less of a sense of "community" these days. Adults are not at home as much as they used to be, and when they are they do not interact with those living around them. One set of cousins lived in the city and the other lived in the suburbs. Both sets could name each person living in a 2-block radius, tell you where the adult(s) worked and what they did, what school the kids went to and what grade they were in, and the city cousins could tell you the names of the shopkeepers in the neighborhood. Now folks are lucky if they can tell you the name of the people living on either side of them. Good luck on getting the name of the folks living behind them.
All of that as prelude to my professional assessment - that was not the first time those parents had become "frustrated" with the behavior of the girl, and it was not the first time they "went overboard" in dealing with their frustrations.
stay safe.