If Google took samples from millions of different songs that were under copyright and created a website that allowed users to mix them together into new songs, they would be sued into oblivion before you could say "unauthorized reproduction."
You simply cannot compare one single person memorizing a book to corporations feeding literally millions of pieces of copyrighted material into a blender and acting like the resulting sausage is fine because "only a few rats fell into the vat, what's the big deal"