Is this common? Airport scanners are usually face scanners. Iris scanners are almost always for employees with access to critical areas, not for travelers. I know Doha and Singapore airports use iris scanners at the security check. It's probably a growing trend, haven't seen any in the EU, is it already common in the US?

Iris scanners are not hard to implement from a few meters in a controlled environment like immigration.

I would assume Iris scanners are normal - but I couldn't find anything to corroborate that for immigration control in NZ (legally they can, and I thought the equipment did, but I couldn't verify).

There used to be a scheme in the UK - https://en.wikipedia.org/wiki/Iris_Recognition_Immigration_S...