Well, subpoenas are issued
prior to someone being judged guilty. And, I don't know if you agree, but "if you have nothing to hide, you have nothing to worry about" is a very poor justification for any kind of invasion of privacy.
As I'm sure people are aware :-
1. Google DNS tracks all domain queries
2. Chrome basically key logs everything you type into the search bar.
3. Android tracks calls, messages, IMs, emails..
4. Google Fiber has the potential to track even more content
If there were lets say 20 different services, there would be NO way to connect email account foo@email.com with a forum posting from member RedSpike93 to a search for "escorts in miami". Google engineers have already been fired for stalking teens, accessing private info, etc.
Heck, its kind of unbelievable that not too long ago, Netscape was sued for "only" tracking what users downloaded.
http://en.wikipedia.org/wiki/Specht_v._Netscape_Communicatio....