Well, maybe because some parents could care less what their children do anymore. My neighbour got fed up with her teenage son that when he got caught by the police for stealing at the supermarket, she didn't bail him out. She didn't even bother finding out why he went missing for two whole weeks.
When I was very little my mum was very strict with me and my academic results. If I even dared to get a B, she'll cane me. But now when my younger brother gets a D, she was happy enough and even bought him a new bike for it. I think my mum spoilt him, that's why he became like what he was now. Rude and violent. He even called me a whore
just because I enjoyed talking to my male friend.
But I think influences from their friends is to be blamed as well.