[avckp]

Why do they want to store the image at all?

Compare against the stored values and discard the captured image. That should be enough.

[justinclift]

> Why do they want to store the image at all?

If the scanners are upgraded to 3D (likely at some point), it'll make for a good source of model data for future fabrication efforts.

Along the lines of https://news.ycombinator.com/item?id=14786863

[probablybanned]

Auditing, perhaps? If someone manages to enter on a stolen passport I'm sure they'd like to be able to go back and see what image was captured and why the system returned a false positive.