The problem is people are worried they’d wind up in far more trouble than the kids. Most people would not dare put a hand on a ‘child’ because they fear the police would be more likely to prosecute them. And not without reason, unfortunately.
These kids know they can get away with stuff like this because the law will protect them. They just have to claim ‘child abuse’.
With video footage, a court probably wouldn’t convict - but your life would be on hold for a couple of years before it ever got to court.
The real problem is that politicians or police that go after the good guy never have their constituents pay them back in kind.