A second hand kindle is also close to zero emissions. Why compare a new kindle to a used book? A kindle is more a replacement for a bookshelf, and each book within has trivially low emissions
Some (many?) buyers gets the latest Kindle only because they can resell the old one at a good price to second-hand buyers. Can we hold first buyers responsible for all the emissions when others partake in the product life that require new products to be created in the first place?