Dorothy Roberts' book Shattered Bonds gives a damning description of the foster care system, describing in chilling detail how the government is willing to pay social workers to find and "rescue" neglected children, and then pay again for foster homes, but not to pay assistance to the impoverished parents to help them provide acceptable conditions in the first place. Roberts convincingly explains how the adversarial approach of child welfare followed the acceptance of Black families onto the welfare rolls; instead of supporting white widows heroically bringing up their families suddenly tax payers found themselves bankrolling Black welfare queens and their endless hordes of misused offspring, according to the new story society and the government told itself.
Racism permeates the system throughout, from judging which families need help and which get their children removed (it helps to be white to get help, but Blacks are more likely to have their children yanked). It's harder for Black families to get their children back, both in identical circumstances and because of features in the Black community; social workers tend to tread the more widespread use of relatives for childcare among Black families as evidence of parental neglect. Later, if children in foster care come in contact with the law, at every stage Black youths suffer stronger consequences.
There aren't easy answers; Blacks over representation in poverty means that they will be over represented in child abuse, neglect and other foster child situations. I can't argue that parents strung out on drugs are often dangerous to their children, but the many cases of social worker abuse and insanity make it clear that something is broken.
The book itself is ten years old, which leaves me wondering what has changed in the interval.