Even in today's world of fact, variants of these three approaches from the world of fantasy are still the only options for secure identification and authentication. The technologies have been perfected. They're very cost-effective solutions. If you realize how much it costs to keep a system working with PINs and passwords, biometrics is a no-brainer. I imagine that in a couple of years it'll be hard to find a hospital that isn't using biometrics to secure data in some fashion.
All biometric technologies have strengths and limitations, depending on the problem to be solved.
Voice-recognition systems may be fine for call centers or a quiet environment, but they're disrupted by background noise. Iris scans are super-accurate, but the technology has been cumbersome and is still relatively expensive. And so on. In addition, it would be unobtrusive, easy to use, readily accepted by all users and, of course, cheap. Unfortunately, maximizing all these values at once is probably impossible.