My professional background is in social work (mainly with adults rather than children) though I now work in a different (but related) role. I think most social workers, health visitors, etc are doing a good job in difficult circumstances - few set out to make people's lives miserable!
But leaving aside issues of underfunding etc, as in any job there are people who are just not suited to the role. When I was training and doing my placements (I was a 26 year old single parent at the time) I kind of naively expected everyone would have great values, etc, and was shocked to find this was not always the case. I've worked alongside newly qualified young people who are well meaning and intelligent but lack life experience and are overly judgmental. And older staff who are cynical and inclined to see the worst in people.
I worked with a woman in her late 30s with a fairly mild learning disability, I'll call her Lisa, who was unexpectedly pregnant (result of a consensual one-off), she wanted to keep the baby but was terrified she wouldn't be allowed to. I was the first person she told and I could see how frightened she was - she couldn't stand her previous social worker and was afraid I would immediately tell her off (her words) and say she couldn't keep the baby.
Her family background wasn't great and her younger sister had had children taken into care. Cue lots of meetings during the pregnancy, and most professionals were of the view that Lisa obviously couldn't cope and the baby should be removed. A large part of the argument was based on the experience with her sister ("we gave her a chance and look what happened"). I felt this was unfair, she was an altogether different personality to her sister, and although she would need support, I felt she may well be able to cope and should be given a chance (and advised not to take parenting advice from her sister!).
We managed to get a support package in place (nightmare in itself, but that's another story) and she had the baby and coped really well. I don't know what happened in the long term as I moved away from the area, but I hope they thrived.
This was quite a long time ago , but I suppose I'm just thinking about how wrong decisions can be made based on incorrect and unfair assumptions. I could give other similar examples.