Samsung are a global behemoth, they have huge economies of scale. They can employ staff wherever on the planet it's most cost effective to do so. They manufacture touchscreens, processors, memory, etc... - components their competitors would have to source from third parties. Should Samsung choose to match ZTE's and Huawei's price points like for like then I'm sure they could, however I don't think they will because they don't have to. Certainly not at the moment. Samsung have a standing and a reputation that ZTE and Huawei are currently still a long way from achieving.

Setting your price too low can actually give a perception of poor quality that is counter-productive.

NOKIA better watch out for ZTE and Huawei though, they're both reported to be planning WP8 devices and the NOKIA brand is now so tarnished with failure that they're much more likely to have to slug it out on price. NOKIA's margins are already tumbling and WP8 doesn't even give them any possibility of customisation or differentiation so imo it's much more likely to be a feature for feature slap down.