They buy into the Kindle brand as opposed to just purchasing a tablet.
Even more evidence that there is no such thing as the “tablet” market. In my own experience there is an iPad market; people ask for it by name. The only other tablet type product that has the same presence is the Kindle, which people also talk about by name.
In real conversation with average consumers (as in people who wouldn’t care about the content on this site or the sites I follow, like The Loop) I have never once—not ever—heard someone say they were considering buying “a tablet.”