> What prevents EA from moving their studios to Poland or China?

Culture, for one thing. Especially game series like Fallout or GTA live from the absurd amount of US-centric cultural references in even the tiniest details.

GTA is developed in the UK - but I suppose there is at least no language barrier.

Really? So you are saying people from China can't chung out copies of NFL with slightly higher numbers? Because those are EA's bread and butter.