Speaking as a foster carer for many years I will say the SS process is never to remove a happy, very much loved child from his/her parents for no reason. Also babies are not removed and immediately placed for adoption "because it is in the best interest of SS".
Every case is different. In ALL cases parents are given every opportunity to display that they can provide "Good enough" parenting. Once this is displayed the child returns home under a well thought out care plan. If there is no progress being made, in terms of parenting, other family members are invited to apply to care for the child. There will be assessments made on the alternative family members, and contact arrangements set up.
In my experience very rarely do family members put themselves forward to care for their grandchild/dn/younger subling. Some do, initially, then pull out during the assessment period or fail the assessment. This process is not quick, easy or straightforward. It can take years - by which time the window of opportunity for the child to be placed with a loving, forever family via adoption has gone.
I, and I know many other foster carers, have adopted children because by the time SS have given their birth parents and birth family opportunities to sort themselves out the clock has stopped. One of my foster children spent 9 years in and out of foster homes. Another spent 7 years in foster care whilst the parents were intent on taking SS to court over varying disputes, rather than spend the time concentrating on getting their children back home.
The process is never straightforward. Every parent is provided with ample opportunity to have their children returned. I have been involved with some brilliant SW's who focus on the child's needs and go all out to help them return home. Sadly, this depends on the parents and not all parents are capable of "Good enough" parenting.
I have also met some nasty, conniving, vindictive SW's. Their stance is, usually, backed up by the team manager. Once a stalemate has been reached between vindictive SW and child's parent I am sad to say the child does not return home. I've had over 100 children to stay. Some very short term, some long term. Only twice have I dealt with two separate SW's who were determined to thwart the parents attempts at returning home. One I don't think the child would have returned home anyway. The other I reported the SW as I strongly felt the children involved should, and could have returned home. I was then accused of not being able to work with SS.
I have also fostered children who have been removed from their parent. Yet the new born has remained in the care of the parent because nobody can say for certain that the baby will be abused/neglected (even though the older siblings have). It's not long before the baby enters the care system though. It's bloody sad that a baby has to experience suffering before SS can prove the parenting he is provided with isn't "Good enough".
"Good enough" parenting means very basic parenting. Mainly that the child is kept safe and all his basic needs are met.