Sorry but I have to disagree. Parents these days refuse to accept blame that their little darlings do anything wrong.
Well, you disagree, but from direct experience, of my own, on both ends of it, the parents are the last to know. Now, they may suspect something and see something is not right, but that doesn't tell them what it is.
The fact of the matter is that the kids kept things from their parents 50 years ago (and I know this from myself and other kids, too). You'll never convince me that parents really "know" what is going on... LOL..
And today, having been involved in it from being somewhat conversant with what soe youngsters do (with me not having any parental authority over some that I've been acquainted with), I also know that they get away with a lot that their parents never know.
If you say there are parents who "know" what their kids are doing, I'll come up with 50 who don't know and although they may suspect, they just don't "have a clue"... :-)
Now, they may suspect something and see something is not right, but that doesn't tell them what it is.
If they do then they ought to find out what their child did wrong. I don't allow lying in my house. My children (all now adults but the 10 yr old) know it & they know if I catch them it won't be pleasant. I am lucky they still fear mommy somewhat or they just don't like it when I get upset. Whatever it is I am glad it still works. I also think some parents are like my parents were, they just don't care to know what is going on. As long as the police aren't at their door all is fine. But I still say many parents are quite aware of what their brats are doing. And you won't change my mind. I have 6 children & a few I've fostered along with them. It all comes out & they tell on each other. Or you hear them talking. I am a nosy mother, lol.
And sometimes the parents are the last to know because they will rip off your head and leave a bloody stump for a neck if you tell them something they don’t want to hear about those darlings.
Been there, done that.
They can then deal with the consequences of their delusional parenting.