Couple things:

1) For the past three generations, societal changes have been driven from the teenagers up, not the other way 'round. Tony Judt makes a pretty compelling argument in Postwar that children with no adult responsibilities and a disposable income (however modest) were a new thing in the world, and that the Baby Boomers were really the first generation of "teenagers" the world had ever seen. The social movements of the 50s, 60s, 70s, 80s, 90s and 00s were all driven by teenagers. I don't think you can say social changes "hit teenagers the hardest" when they're the ones with the baseball bats.

2) Cars are a big part of it. In an environment where an entry-level Honda is $20k and a BAC of .01 means losing your license for the foreseeable future, there's a powerful disincentive to get around by car. Unfortunately, it's the only way to get around for much of the country. Personally, I owned over a dozen cars between the ages of 15 and 20, at one point having five to my name. That was deviant back then but it's extraordinary these days. At the same time, it was a fuckin' hour drive (at 80mph) to a goddamn Taco Bell so it's not like we were gonna ride bikes.

3) I'm not sure "winning" has much to do with it. Consider - it isn't just American teens that are finding themselves isolated. I'd also point out that the culture of "everyone's a winner" has been thriving for the past 20 years. This is also the first time in my long memory that the necessity of college is being questioned. And it's being questioned mercilessly. There sure wasn't no Khan Academy back in my day.

4) Parents are easy to sneak stuff by. In part, it's because lots of parents would "rather not know" - plausible deniability is a powerful thing. You don't need ICQ to pull a fast one on the 'rents, it's just another way of doing stuff. On the contrary, if I wanna throw a keylogger on your laptop you have no secrets from me. There is, therefore, a tacit approval of all the sneaking. I sure as fuck didn't walk around with an Apple LoJack 4S in my pocket when I was a teen.