The sweet thing about secret agencies is that they don't need to KNOW who uses that ip, they only need to guess correctly. And even when they don't guess correctly, you still can be catched in their net wrongly.
They are not the police. They don't need to prove that you are guilty. They catch you away and you rot in some hidden prison. If they are not so sure about you then they will ask you, maybe abu ghraib style?
The police would be more your friend because they abide the law. I am sure many people are hurt in one way or another because of association (Sharing the same cellular id, being in the same place, using the same Tor exit node..)
People nag about metadata collection but I would advocate for content reviewal because metadata analysis can be way more dangerous than actually knowing who is who and doing what. Where the secret agencies can cause you security problems while in fact they should protect you being part of the 'larger national audience' , I think privacy is not very relevant anymore.
Ofcourse this is at the chokepoint where normal citizens, or even police working on the edge, get mixed up with criminals altogether. If only the secret services would have different ways of evaluating things, citizens would not waste this much time on anonimity services.
