That system is complicated. They do monitor the parents. But there are people on it for money. In fact you can make a good living out of it. By the time CPS takes kids, something is definitely wrong. Remember that CPS has to take you in front of a judge to take away your parental rights. They have to prove their case with hard facts. Without which, theres little they can do. You can put them to task with an attorney.
Remember that if CPS are called about a complaint for one child, and they find such valid, they will take all your kids away. Permanently. Usually they come and investigate and give you a warning,