They are of decent quality, though sometimes the cover art might be lower-resolution than that of an equivalent book from a bookshop. I double checked and all of these were sold by Amazon themselves (i.e., not a marketplace seller, where I would suspect a piracy issue). The cover material is always this unpleasant matte rough-feeling paper.
Is there anything nefarious going on here? Does Amazon have permission from the publishers to distribute their books like this? The books that I received were of different publishers (Penguin, Basic Books, among others).