Goodreads isn't uploading the data. I don't think Goodreads even uploads books from Amazon--they just connect to it if there's also an Amazon listing.
Miscellaneous people with accounts on Goodreads are uploading AO3 (and occasionally other places) metadata. And this is not so much to Amazon's advantage (they gain nothing from fanfic being listed, and occasionally will have drama over it), but it also costs them nothing, whereas curating book listings would take a lot of time and effort.
Basically, they're not going to sort out the difference between a story published at AO3 and one published at Smashwords, or one published at NewStoriesEveryDay.com, or whatever other fic-hosting site shows up. Listings take up very little server space, and the cost of curating would be much, much higher than the cost of "just allow everything, and remove individual pages when we receive a creditable complaint."
no subject
Miscellaneous people with accounts on Goodreads are uploading AO3 (and occasionally other places) metadata. And this is not so much to Amazon's advantage (they gain nothing from fanfic being listed, and occasionally will have drama over it), but it also costs them nothing, whereas curating book listings would take a lot of time and effort.
Basically, they're not going to sort out the difference between a story published at AO3 and one published at Smashwords, or one published at NewStoriesEveryDay.com, or whatever other fic-hosting site shows up. Listings take up very little server space, and the cost of curating would be much, much higher than the cost of "just allow everything, and remove individual pages when we receive a creditable complaint."