With the iris scanning, how about getting the person to follow a small dot around the scanner with their eye and an iris tracker can confirm it's doing so.
Any security solution that depends on technology can also be defeated by technology.
In this case, you would have to have a system for tracking the eye, which would be defeated by a system for tracking the dot. Plus, you'd need guards against feeding the system wrong data at multiple points, or bypassing the tracking altogether. You'd multiply complexities unnecessarily, and only end up with another system to keep honest people honest.
Executives[*] who base their "knowledge" on Hollywood movies and detective stories are to blame for big business buying into biometrics for authentication. It's the worst thinkable system possible, because once you have defeated it, you have defeated a living human person, who cannot change his compromised biometrics.
The implementations fly in the face of ADA and similar measures too, directly discriminating against people who cannot use the systems. Some don't have fingerprints. Others cannot stand and look into the iris scanner. Or don't have eyes to look into them with. So you must have a backup system anyhow. That prompts the question: If the backup system is trustworthy, why not use it instead?
[*]: And unfortunately not just business execs. As late as last week, a police superintendent was quoted in a big newspaper saying that DNA evidence is 100% trustworthy and (I kid you not) we should never question it. The newspaper didn't even question that statement or ask an expert for opinion.