What you've posted are decidedly middle class attitudes. Some children raised by parents who think the way you've described way may be snotty and have discipline problems - perhaps severe discipline problems, in some cases — but almost none plot during school hours to rob people right after school and end up jumping young women from behind and stabbing them to death. You can bet the thugs who committed this murder have been reared in chaotic households where “spanking” means getting smacked by Mama's latest boyfriend whenever he's drunk. Their families are probably on welfare, yet consistently come up with cash for cell phones and Nike sneakers. Am I saying these young teens are not responsible for their actions? No; most of the kids growing up that way don't go around stabbing people. These particular boys happen to be innately violent and probably have low-IQs, although low on the normal range; they are not intellectually disabled, though their lawyers may try to argue they are down the road.
The parents you've described may be naive and obnoxious, but visit certain neighborhoods in NYC and you would be astounded at how minor the faults of the parents you've described are in comparison to those of the types of the people who pass for parents — well, mothers, as the fathers are largely nonexistent — who are rearing the kids like the ones who murdered poor Tessa Majors.
I fully understand your point. I used to own a supermarket in a very depressed neighborhood. I saw, and experienced plenty.
The problem is much more complex than anyone can describe in a few words here.
My point is, it starts in the home, family, schools, and neighborhoods. When those fail, the kids do too.