Its about fragmentation, Europe is fragmented by countries (governments), language, culture and law. US and China, not so much, a company has an immediate larger reach, and has less scaling issues than it would in Europe. Consider also the access to funding, how many small pots of money is there in europe all disjointed, compared to funds in China/US. Consider the focus companies can get in China with government support, its what makes china such a threat to the US. US has arguably accelerated areas via military R&D.
