[oakhaven]

I think there's a lot of sideloading. Buying non-{english,mandarin,spanish} books happens often in other book eshops, usually language- or -country specific. If you supply your kindle ID, they are able to send it straight to the reader, but the book collection is then stored in the local eshop (or more eshops if you buy from multiple). That's why Calibre exists.