I don't see how those kids having a complete and total lack of respect for someone in a position of authority isn't proof of poor parenting. Likely whatever discipline they receive at home is completely ineffective. If my daughter had been on that bus, she would've been yelling at the other kids to stop. Not only because she's been raised to respect those in a position of authority (so long as they don't abuse it), but she'd know that corporal punishment and removal of prized possessions would be waiting for her arrival at home if she did otherwise.
Evidence, yes. Proof, no.
My son has been tested in a remarkablely similar situation and he did stand between a group of bullies and their victim on a school bus.
But it is simple. I give him credit for that being partially what I have taught him, and partially his understanding that he would have had his ass beat for it. But mostly I credit his personality.
There are aspects of personality that parents can not control, nor shape. To oversimplify it: some children will grow to enjoy being cruel to others and some will grow to enjoy being kind to others no matter what a parent teaches them.
There are some children who teeter on the fence between the two who will be influenced one way or the other by their parents' teaching. But those are very few.
Then there are kids with good parents who go bad and there are kids with bad parents who overcome that and become great adults. That can be seen exemplified with very little looking. Parents can teach right and wrong and lay the groundwork...but in the end, the individual personality will determine which way the individual goes.
And when you add in variables like peer pressure, inexperience, and anonymity when the true authority figure is not present (the kids know the woman on the bus can not do anything to them, but if dad was there...it would be different), those lines of discipline will get tested sometimes...even with kids that eventually grow up to be good people.
