Agreed, but i think you would find that the corporations do wield an amazing influence over those in power. A lot of people would find it hard to distinguish between capitalism and government.
I'm not saying that a lot of corporations try to influence those in power, and by no means am I saying that a lot of corporations do what they can to get out of paying taxes.
What I'm saying is that capitalism is an economic system, not a governmental system. They are separate entities, although interaction between them does occur.
Communism, on the other hand, is both an economic and governmental system - the two are tied together. This is what (if I understand it right) makes the system in China a sort of pseudo-communism - they have kept the governmental portion (to a certain extent), but have adopted a largely capitalist economy in order to avoid a Soviet Union-style collapse.
(I could be totally wrong on my analysis of China, as I have not studied modern China much at all.)