If we just consider official channels, I quite expected these results in Brazil, due to fiscal reasons, having a production plant there favours MS and in Mexico, due to close commercial relationships with USA, but I didn't expect it in Argentina. Initially I thought the numbers didn't add up, but Mexico, Brazil and Argentina, despite being just three of the many countries in Latin America, include a very large part of its inhabitants.
I too expect this to change as soon as Sony starts or licenses local production in Brazil, finally avoiding monster import duties there.