The X360 isn't American made, it is made in China, just like the PS3 and Wii.
When an American buy an American made product it is typically stuff like Craftsman, which is American made, or Ford. Things that are actually made in America.
Also, maybe people buy the system that has the types of games they like. XBox 360 has Halo, Madden (has had xbox exclusive advertising in the past) and other games that Americans like. Also, as noted, the Wii has outsold the X360, and that is supposedly the casual machine, not the X360.
XBox 360 has some Japanese centric games, however, they were mostly all bought by Microsoft and you really wouldn't have expected those types of games to be on the XBox 360 in the first place. So instead the Japanese buy the Wii or PS3 where they expect the type of games they would like to be.








