IDK about Minnesota, but in Europe this is not the case. The vast majority of kids getting taken away get taken away for 1 reason only:

Some social worker (and there's lots of them) complains that they've refused necessary help. Of course, kids refusing help has direct financial repercussions for these people.

That's over 80% of placements (and let's not forget close to another 15% are kids getting arrested for crimes). Kids actually having seen physical abuse are very rare IN CPS. Hell, these days the proportion of kids that have gotten abused is higher in "Juvie" than in CPS institutions (most of these institutions will refuse kids who have "trauma as a first problem". Likewise they'll refuse addicts, anorexic, outwardly or inwardly agressive kids).

Issue is that what is never mentioned is the success rate of these social workers. Most often they're there to fix autism (and not autism like you've seen in documentaries, "autism" like refusing to listen to parents/teachers on occasion). Almost without exception problems exacerbate with these treatments (one simple reason that these kids are often smart enough to coast through (often primary) school. However, if they are denied school attendance (because social workers work during school hours, of course, so treatments happen during school hours), obviously they start failing more and more.

Given social workers' education (ie. high school, a VERY low course level in high school, sometimes not even having finished it) they are also incapable of helping out with most problems. You can't help a kid with math problems if you don't know math. So they should have a level of every subject given in high school, at least the level of teachers. To put it very mildly, they don't.

A bunch of these kids understand what is happening and start fighting social workers. This then leads linea recta to CPS involvement, mostly because these are very young kids. Violence works against them (read on), but these kids are too young to effectively use violence against an adult. Instead they cry and refuse to go or run away or the like.

Of course, the net effect is that CPS starts protecting their real clients, the ones who provide them new business: those social workers. Attacking the kids who asked for help, then refuse what they got. With threats, which doesn't work well, then, via youth judges, with violence.

And, the other side of the coin CPS becomes actively hostile to kids with real problems, whether that's abusive parents, drugs, criminal involvement or school problems.

They are very often accused that they do not protect kids. If the parents and/or the kid is really violent, CPS and social workers will keep their distance. Again some kids use this to "fight free" from CPS. The problem with that this that these kids are inexperienced, but trying to systematically escalate violence against adults, because that's the only thing that can get them out (and often back into a good school: CPS gets extra money if kids go to "special needs" schools). Issue with that is that "dosing" violence to the right level is hard for people who've done it as police agents for 20 years. Kids regularly use too little ... and too much violence, both of which have essentially the same consequence: getting locked up in isolation 23h per day for a period from 2 weeks to several years. And of course, this affects CPS employees: only the worst of the worst remain.