The children who behave like this don't always come from obviously chaotic households. Very often, they're from "nice, middle-class" households where parents can't say "No!" to their offspring. (Yes, I know that that is not gentle parenting.)
I'm basing my comment on my experiences in secondary schools. Elsewhere on here, I've told of how I was punched in the stomach when I was pregnant (but not obviously so). I was in my 40s, so kept myself sane by telling myself that I would have probably lost it anyway - I never managed to reach beyond the first trimester.
One pupil was assaulted and then I was punched. The two male teachers who came to my assistance were also punched. The local police "lost" the statements. (The boy was below the age of 16, so it wouldn't have gone beyond the Children's Panel here.)
I couldn't prove that I'd ever been pregnant: I'd been waiting to re-test, because I'd only got a faint positive. Being an idiot, I didn't want the boy to be stricken with guilt.
Some years later, I found out that this now adult male was boasting about punching me - I had girls coming into my class giggling about it.
This was a boy from a "good" home. Around the same time, another boy punched a male teacher who happened to be of small stature. Again, a boy from a "good" home. (At least in his case, the police got him for breaking into cars as soon as he turned 16.)
Behaviour in Scotland is becoming increasingly worse in schools. I do occasional supply. A visibly pregnant TA was punched at my place of work earlier this year.
I can't speak for what's happening in England, but in Scotland a huge part of the problem is that the courts won't deal with those under the age of 16 here. If anything happens at all, it's a referral to The Children's Panel or SACRO. (My assailant was referred to SACRO 20 yrs ago. He told them I'd "got in the way". Translation - was desperately trying to keep my stomach away from him. They wanted me to have a "restorative conversation" with him. I refused.)
I can think of one boy who did actually finish up in secure accommodation. He'd set light to a homeless person.
To my mind, the only way to stop the rot is to bring back meaningful consequences. Teenagers - to my mind - just see "Restorative Justice" as a kind of weakness.
I'd also want to see strong penalties for teenagers who film assaults and upload them to social media.
Another problem that I'm seeing here is that when the problem is a chaotic household, social workers are reluctant to remove children from that household: "The best place for them is at home."