In your example, what if the leader's of financial companies did behave? Then is the system the opposite of corrupt?
The system itself is amoral and impartial. The people involved in that system decide whether corruption exists or not. A system can be designed to combat or prevent corruption, but people always find a way around it.
Is Communism corrupt? No, the ideology of Communism is not corrupt. It has the interests of the people at its core. However, as we've seen time and time again, Communism doesn't work because despite its best intentions, the people in control find a way to manipulate the system to service their needs at the expense of others.
In that case, you would have people behaving well in a corrupt system. I should note that the reason a system like that gets created is generally from the pressure of the big finance interests who will benefit corruptly influencing the government to pass it; and that I know of no case when such a system has not been abused for 'corrupt' activities.
Our current system has some protection from judges having conflict of interest. How about we make the system remove all those rules, so if the judge is hearing a case he will benefit in financially between his family member and a stranger, that's 'no problem'? As you say, maybe the judge will rule fairly, even for the other side. The system is still more corrupt than not allowing that sort of conflict.