I'm pretty sure that most of you noticed the difference in the Microsoft search engine Bing when switching between languages on the top right corner! Actually the ones other than the United States are so basic and have no home page "add-ons" that we can see on the United States one, like hovering over an image and getting more information about the background, the quick list at the left and a lot of others.
What are the secrets behind that? And why they don't make all the domains (if we can say so) with the same functions with different UI language?