While traveling on vacation, I experienced who real-world security measures, neither of them having to do with the TSA.
The first was having my credit card declined in an airport in Houston. I’d used it the previous day in Boston and Vermont, and I guess that was enough to raise their suspicions. Although it was mildly inconvenient, I was able to finish the transaction a minute later with another card, and I recognize the fact that this was a security measure designed to protect not only the card company, but myself from fraudulent charges. This is not unlike having a computer account locked after too many invalid logon attempts.
Shortly thereafter, I logged in to Facebook on my iPhone. Facebook decided that my IP address looked a little suspicious, given that I had just logged in from Boston a few hours before. I logged in, verified my account and was able to proceed. I then had the pleasure of repeating this process minutes later, as Facebook then realized I was in Brazil. Again, the inconvenience of having to simply log back in to Facebook again to prove my identify was minor, and the added security gained from having to do so was worth it.
Given the alternatives of having unauthorized charges on my credit card or having my Facebook account compromised, I’d much rather endure an occasional minor inconvenience.