One reason is value. They produce so many, the quality is decent and the price is subsidized so it's artificially low.

Why is it subsidized? Obviously to make it more fun to buy books, but also collecting valuable data on your reading habits. Obviously they know _what_ you're reading but it seems useful to them also to know what you bookmark etc.

They also have all the hardware they need for location history tracking by remembering wifi broadcasts seen. Is it known if that's being uploaded?