I think that most kids of every generation are a bit rebellious, but I also think that discipline is getting more relaxed as time goes on because it takes a lot of time and effort, which is one thing that people are getting less and less of.
Both parents feel they have to work more to achieve the American dream, so they have their kids in after school programs or with a babysitter who just can't give the children the care like a father or mother. Parents also spend more time commuting because we are moving further away from our workplaces as suburbs pop up in areas that were formerly for farming.
At the same time, kids activities also take more and more time, so when a parent gets home after a day of driving around, the last thing they want to do is manage their kids. So they keep them inside where they think they are safe and stick them in front of a tv or a computer, which is where kids are getting their life lessons from.
All this is assuming parents are married; single parenting compounds these problems even more.
I always hear people say that kids are changing, but the reality is that it is the parents who are changing with every generation.