You can pick your friends, but not your family

So I have a younger relative who seems to just want to drive everyone nuts lately. Yes, she is a teenager. She used to be so much fun to hang around, we always got along very well. Now it seems that her friends rule her life and push her to make stupid decisions and think her family is just awful. She had it easy growing up, trust me. I swear that sometimes I just want to bitch slap the whole lot of them and tell them to get over themselves. I remember being a teenager and try to carry that when listening to her, but I don't remember ever being that bad. Maybe I am just getting old.
So on to the kids of today issue, are they spoiled little brats? Not all, but they have lost the fear. I respected my parents because I also had some fear of them. Kids have no fear of their parents today, they just threaten to call 911 when not getting their way. I don't support child abuse, but some of these kids could use a good butt kicking.
In our efforts to stop abuse have we leaned to far the other way? Why is it so hard to find a happy medium? When did the government start getting involved in the way you raise your kids?
I know some people are probably asking "why do you care, you don't have kids?" I may not have them, but I still have to deal with them in public. If I acted the way some of them do today, my Mom would have slapped me up side the head, and I would have deserved it.
So how do I deal with this younger relative? For now I tell her what a butt head she is being and tell her to grow up and get over herself, while patiently waiting for reality to catch up with her.