I think this is one of those things that seems like it should be easy to automate, but actually has lots of hidden complexity.

They probably don't use this to scan commonly available books, because for those you can just cut the spine off the book and scan the pages in a regular scanner.

This is likely used for books that need to be preserved and can't be damaged during the scanning process.

How do you make a machine that will always turn exactly one page and never tear a page, while adapting for different page sizes and thicknesses, and avoiding the static charge that can make pages stick together? All for less money than it costs to pay people to operate this machine.