Amazon thinks all internet users come from United States

Sat, Mar 1, 2008 Tweet Vote on HN Recently when trying to "Sign Up for Amazon Payments" I had to login and then the form shown to me had only United States as an option. Couldn't find an explanation for this anywhere. My account as my Thailand address listed. Why does amazon force me to accept that I am from US? Or is it that they seriously believe that people outside United States don't use the internet?