China or Saudi Arabia can wave their money around, but at least some people will be repulsed by the obligation to keep their mouths shut and praise the Dear Leader.
Their cultural insularity does not help either. You can live in China, but you will never be accepted as Chinese. The US was quite unique (together with Canada, Australia etc.) that it was able and willing to accept you as an American even with a funny accent, as long as you wanted to be one.