I think about this often too. I think the answer ultimately lies somewhere in the realm of "history is cyclical." A society's collective memory seems to fade after a few hundred years.
America today is an excellent example of that. The founders came from a time of tyranny and oppression, and worked hard to try to prevent that in their new country. And yet a lot of how our government today works is, I imagine, very much contrary to what the founding fathers envisioned.
You can be detained for seemingly no reason by police almost anywhere (see the ACLU's "constitution-free zone"), prisons and courts have become a means of revenge, not justice or rehabilitation, the president is increasingly seen as a king-like figure ("Something's wrong with the country? Must be the president's fault. What's he going to do to fix it?"), and--without much exaggeration--we're a small jump away from a total surveillance state, as this article emphasizes. In many ways we're already there, and that's just the stuff we know about.
In Europe, as you mentioned, the Stasi were around until just recently. There are still grandparents alive who remember what the continent went through during WW2. (My own is one of them.) European society's memory is still fresh, and they won't repeat mistakes they remember. I think that's why there are so many privacy-protecting laws enshrined in the EU.
We should pay attention to how countries recently emerging from oppression or war, like Romania, Serbia, or Bosnia, handle the internet. I'll bet they'll be the bastions of internet freedom in the coming decades.
But what of the US? Maybe we're trapped in cyclical history. Maybe in 50 years things will be bad enough for people to get up in arms, and we'll start over just like we did a few hundred years ago. Who knows.