My wife managed a newborn nursery at a hospital whose customer base was heavily represented by illegals and other lower lifeforms. It was not uncommon that she would see a drug mom on her third kid (and sometimes fifth pregnancy) before the age of eighteen. The State would do nothing. The system doesn't help those kids because they are hard to adopt.
CPS gets an extra $40,000 if they adopt a child quickly. So they consequently focus upon confiscating kids who are easy to adopt. In addition to their ideological predispositions (here in Santa Crux, CA, the CPS office is reportedly dominated by lesbian women), that's why they raid upper middle-class, white Christian families.
When trying to figure out why govt workers are doing something off the wall, "follow the money" is a useful investigative policy
Also, a raid on a middle-class home is less likely to get you shot, and the neighborhood erupting in riots that will be blamed on you and your dept, then trying that in the "inner city" areas where a disproportionate amount of abuse occurs.