I am not implying they are better, just they know english better than the rest of the non-anglo world.
And great communication skills is a preferred trait in solving problems.
Btw, I can code fluently in over 10 programming languages, but my fluency in english is subpar. See? That's why I rather take a cut in the rate as long as they accept my deficiency in english.
If you're expert - you're expert, country does not matter.