OK so what you have right is that corporations and people buy the political prcoess.
What you don't seem to understand is that in non market systems corruption doesn't dissapear. The who gets what is simply resolved by a political process instead of markets.
You get a more centralized point of failure that the corrupt people will take over to get what they want.
Markets give the buyer the ability to put a check on the power of producers by being able to choose not to buy from them.
Polictal processes do not have that check
