I just went to amazon.de and looked at a book and I saw "Jetzt kaufen" which translates to "Buy now". Yes that was a Kindle edition. amazon.com won't show me a purchase option because it wants me to buys Kindle things on amazon.de, but below the bookw, pointing to other Kindle editions (I checked) it shoes "What other items do customers buy after viewing this item?", so there too it uses the word "buy".
I see a "Buy now with 1-Click" button on content I haven't already purchased. There is a "deliver to" dropdown, but it just selects where the content goes after I click that "Buy now" button.
Amazon US: "Buy now with 1-Click®"
Amazon DE set to English: "Buy now with 1-Click®" (German: "Jetzt kaufen mit 1-Click®")
Amazon FR: "Acheter en 1-Click®" [Buy with 1-Click] (there is no English option that I can see)
Amazon JP set in English: "Submit Order" (Japanese: "注文を確定する")
It's not universal, but many of the sites use "Buy Now". The "Deliver to:" box is below this, and sets which device the purchase is sent to.