I reckon you are pretty much correct about this.Many cases I know of that involves serious child abuse also involves overloaded child protection caseworkers, or caseworkers that haven't had adequate training.
Many involve parents whose mental health has been severely compromised - often by their own traumatic childhoods, and a lack of mental health and practical support services to help them cope.
Some of the strategies that I also outlined in a previous post cost money. and taxpayers and governments just don't want to go there. They often prefer to put their heads in the sand when addressing the issues comes with a price tag - even if the long term cost of inaction is far greater.