Facebook - facial recognition is enabled
nakedsecurity.sophos.com
nakedsecurity.sophos.com
One solution is to spam photos of yourself with false timestamps and geodata.
Example: I want to photoshop a picture of my friend onto a dog; I could either load all pictures with him tagged in it, or laboriously go through all of my pictures from a given weekend, hoping that the picture I'm looking for is there.
Result: http://i.imgur.com/C6mrd.jpg
I've also been searched numerous times (although I guess it's small, considering how much I fly). If facial recognition could help in identifying criminals (starting to sound like Lie to Me), I'd be for it.
Right to privacy. Even people with nothing to hide don't like being monitored.
I don't see how it would help in your situation either. "Lots of stamps" is annoying to passport control regardless of any other factors (just because you're not a listed criminal doesn't mean you aren't up to something), and I don't feel like the detainment time is going away anytimes soon for these kinds of things. Even if the information is easily accessed, you have to wait for the decision-maker to spare some time to consider the info and give you the OK.
In a similar vein, one example is Megan's law, named after a young girl who was murdered by a convicted sex offender. The law was enacted to create a registry of such offenders to let people know when a sex offender would move into new neighborhoods - a modern day Scarlet Letter. The idea was "fine" in theory when it came to child molesters, but since then the definition of "sex offender" changed, which now encompasses near-age-consenting kids who would send each other risque pictures or an 18 year old having sex with a 17 year old.
There are just examples, but that's why "nothing to hide" doesn't work in our favor.
Your second point is correct: the law is to be interpreted, and anyone can be convicted of a crime, if the prosecution tries hard enough. However, that's a very specialized case, and there isn't someone out to get everyone. Even being wire-tapped and watched 24/7, chances are you'll never interact with the people watching. If there's almost 0 chance of someone interfering with your life, why does it matter if your privacy is lost to them? I'm not trolling or playing devil's advocate - I really do not see why it matters. Someone I'll have 0 interaction with can watch me 24 hours a day, and it would not phase me at all. I only bring this up because you brought up terrorism. I also argued (your view) on Ex Parte Quirin several years ago, so I really have considered the subject.
Your Megan's Law example is really a tangent. I don't like child molesters, and I don't agree with statutory rape being subject to such communal ostracism - just like you. In such a case, yes, the law changing has screwed things up. However, it doesn't apply to our original point. You're arguing whether specific information should be publicly available, while I'm arguing whether already publicly available material should be analyzed. They already see your face, just humans aren't able to spit anything useful out.
I hope my point is clear.
Almost 0 is not zero. If you're monitoring 300 million people, and the chance of a false positive is, say 0.001% per person per day, that's still 3,000 false positives every day. The false positive signal far outweighs the signal from the "real" dangerous people, making the system pointless and useless. Even if it works 100% of the time on the intended targets, human operators will become too fatigued from dealing with the false positives to deal with them effectively.
In addition, companies like Facebook and Google have a distinct incentive to keep their product spam-free. This means that, so far as spam and security are concerned, the user's interests are completely aligned with the company.