It's probably the word 'government' that's spooking everyone out. I think most people are conjuring up visions of the NSA telling insurance companies about your medical records and stuff. That or they probably think they'll be sending a SWAT team to your door every time you tweet about getting high or something. The point is, there are already checks and balances that exist to protect your privacy. Just because an organization has collected your data, doesn't mean they can look at it. Your metadata, no matter how much you try to hide it, is visible to a lot of people. Hell, your ISP probably uses that same metadata for all it's marketing and operational planning anyway. I personally don't think the US Justice system is so impotent that it cannot impose effective safeguards on the government.
I think your right. While evil corporations can collect and profile people they don't have the ability to put you in prison, so there isn't this relationship between privacy and freedom. And I think that people like to feel that it has some impact on their lives because it puts them at the center of the issue. We can all relate to having our personal privacy violated, but its harder to have a conversation about having some people's privacy infringed upon especially when there is a little bit of mystery around the topics that the NSA is really monitoring. I'd probably get concerned if this were happening at a state level, where the police were involved in data collection, or if this were actually something new. But people still post about underage drinking on twitter, and talk about drugs on facebook, so I'm not really concerned. That and I like knowing that there are people in the world that have bigger issues on their hands than cracking down on those kinds of things.
In fact, a lot of people like to think that the real issue isn't privacy infringement at all, but rather a sign of how large and powerful the intelligence-industrial complex has become. I read something rather interesting on Reddit the other day. Here's the comment. It's quite a handful