USA + Europe + Japan sales are closer to WW than you think. Because at least in South America many people buy the consoles from importers (many of them don't enter to the country legally, they don't pay taxes so they can sell the consoles cheaper) who buy the consoles in the ports of Panama or Venezuela (from american flag ships) and then re-sell the consoles in their countries, so they are registered as sales in the United States (Almost all the games sold in South America are the same NTSC games that are sold in USA). That's why you could buy a ps3/xbox360/Wii in any country of South America almost the same day it was released in NA.
I can imagine it's almost the same in other regions from the Third World.
I know... my english sucks