A possibility would be that you might want to make multiple changes in light level at random intervals to make it harder for e.g, a video being presented to the camera that matches the input it would expect.
That would make sense, certainly what I would call a further stage of development and currently they are doing viability and a basic level of operation. So that would seem like a logical progression.
Coz they could add a brainwave scanner that measures the reaction to the input of the eye, or have a higher resolution camera that measures blood flow being active in the eye. Many avenues of addressing this. But as a previous comment mentioned - generally easier to have a physical person next to the iris. After all, not like there is a shortage of humans to do jobs in the World today.
The LG iris scanner that I've used in the past had a small flickering red LED between your eyes. I'm not sure if it was just something to focus on or if the light was meant to make your pupils dilate slightly. The one I used was probably nearly 10 years old. The newer scanner out there look to be a lot faster and more automatic.
Coz they could add a brainwave scanner that measures the reaction to the input of the eye, or have a higher resolution camera that measures blood flow being active in the eye. Many avenues of addressing this. But as a previous comment mentioned - generally easier to have a physical person next to the iris. After all, not like there is a shortage of humans to do jobs in the World today.