An anonymous reader writes: In reality, fingerprint scanning can be unreliable and difficult to use. The problem with biometric technology is that it is hard to know how it will perform outside of controlled conditions. Fingerprint scanners often wear out over time, and when they come into contact with water, sweat, and dirt, they don’t perform nearly as well. The elderly, which makes up some of Apple’s most dedicated fans, and those who do manual labor are known to have worn-down prints that are difficult for machines to read. The problem then isn’t that Touch ID will let others in, but will keep you out.