Mozilla needs a high market share in order to convince search engines to give it a better contract.
meaning Mozilla will try to get a larger userbase for firefox, so that the next round it needs more money, It can ask for more money from bing/google/yahoo or whoever is willing to pay for the defualt browser spot for firefox.
so do they have paying customors outside north america? no, it doesn't matter, its the market firefox is trying to expand into to get money later