>Not at all perfect. Can that human guard really see if you're wearing a fake fingerprint? I doubt it, unless he's closely examining everyone's fingerprints first. And even then...

The procedure at the USCIS to get my green card was remarkably thorough. The guard manually and visually checked each of my fingertips carefully to ensure I had no fake print overlayed on top of my real print and I had to keep my hands within a small area with a camera on it for the entire process or they would restart everything.