Buying a book made of trees is very often much more expensive than reading on a screen. Worldreader provides books for free for schools in Africa where they only need to pay for a $40 phone once instead of spending money on books.

https://www.worldreader.org/

Laptops and tables are, as it turns out, not so cheap either. They need to be fixed or replaced at an alarming rate, and they lay claim to a much larger part of a school budget than books ever did. That is part of the reason that we revert back to pen, paper and books in Norway. First for 1-4 grade, but it will be push further up the grades as we go, I think.