The reason that children are moved from carer to carer in some cases is because the child has been so damaged by the birth parents in his early weeks, months and years, and the most important time in a child's development is the first 3 years. Children removed from parents will by definition have an insecure/anxious attachment to their parents, because their needs for physical and emotional care have not been met. These children learn that adults are not to be trusted and some of these children will be withdrawn and others will be angry and behave in a similar way to Toby when with his parents.
I have seen foster carers try their utmost with attachment disordered children, to the extent that their own marriages suffer and some suffer from mental health issues. They feel a tremedous sense of guilt that they are unable to cope, but the sad fact is that the damage done in the child's early life cannot always be overcome, even with the best will in the world.
It's the same thing with educational progress and poor outcomes for children in care, and that many young people in the care system end up in prisons in later life. It isn't because foster carers are no good and give up on children, it is in the main because of that early emotional harm the the child suffered when in the hands of their birth parents. OK foster carers and adoptors are like anyone else, some superbly confident, offering warm loving homes, others who are not as good, and a small minority who would be better off doing another job.
Toby had made tremendous progress (even with the little bit that we saw of him) in the contact session after being with foster carers for a few months, and I think this demonstrates the tremendous skills and patience that most foster carers are able to give to these children, but the whole foundations for life are laid down in the first 3 years of a child's life, and sometimes it cannot be changed. Many times it can change, if the carers are given the opportunity to learn about parenting the "hurt child" but it takes an enormous amount of time and patience and the rewards may be slow to come, and sometimes the toll on the carers and their own children is just too much to take. I have seen marriages break up and carers have mental health problems and their own children suffering, so please stop and think of this before you talk about how shocking it is for children to move around placements so much. Of course it is, no one would deny that and of course it is going to make the child more and more insecure, but foster carers are human and sometimes have to end a placement and suffer with the guilt for a long time ahead.
The emotional harm is caused by the birth parents and I am not being unnescessarily critical of birthparents, because many of them are like Tiff and Mike - children trying to bring up children, emotionally immature, having experienced abuse or neglect (or both) in their own childhoods. Earlier upthread Mrs DeVere was giving an account of how this cycle of deprivation can be broken into, but it all sounded rather vague and overly optimistic in my view.
I just wish we did know how to break into this cycle but I am wholly pessimistic about successin that area.