> I don't actually care if they collect my data in that particular case. There's really nothing of significance that Amazon gets from my reading habits that it Visa doesn't already get from my purchasing the book in the first place.
Visa knows you bought a book. That's all they know. Amazon knows that you actually read the book (or didn't), how long it took you to read the book, how many times you read it, every date/time when you opened it, what specific pages you flip to and re-read later, etc. Maybe you consider that data to be "nothing of significance", but Amazon doesn't see it that way. They spend a lot of time and money collecting, storing, and analyzing that data and it isn't because they didn't think it's worth anything.
Visa knows you bought a book. That's all they know. Amazon knows that you actually read the book (or didn't), how long it took you to read the book, how many times you read it, every date/time when you opened it, what specific pages you flip to and re-read later, etc. Maybe you consider that data to be "nothing of significance", but Amazon doesn't see it that way. They spend a lot of time and money collecting, storing, and analyzing that data and it isn't because they didn't think it's worth anything.