Exchange rates aren't a complete picture of global economies, you really have to look at the average wages for people living there. If the average person in these countries is making substantially less than the average US/UK/EU consumer, just setting prices based on the exchange rate may result in games being unaffordable. So it makes more sense to price in those regions based on purchasing power, even if they're making less money per copy sold that's better than making no money by selling no copies.