It'd take a lot more space and time then I have available here to outline my views on most politices, but I will attempt to clarify.
Greed is human nature, I accept that and see that it can be put to use for the betterment of everyone. Greed is wanting to improve, it isn't just the want of more money, its to do something to get a reward.
With a private establishment, its for profit, money - Oh there may be some environment or some morals in it to make the people running it feel a bit better about themselves, but the bottom line is that they're looking for money to spread around in their pockets.
A public company is providing a service for the public, by the public, through the public. Since it is run by the government, there is no profit, its only the service therefore the greed will be different - It will not be for money, but to do good. We do not need to remove greed, just change what its final goal is, instead of money, recognition, and a better quality of service.
Also, private businesses to their very foundation is corrupt since they're trying to pad the pockets of people first, second is to provide whatever service they're offering. This isn't what should happen, there should be no padding, only a service. And as for monitoring - FBI find the records only after the corruption may have begun. If it was public, it would be constantly monitored and would be discovered as it started.
Now, I am going to sleep! :) If any of this doesn't make sense (and it most likely does not), point out the aspects that don't and I'll explain better later on today (Its late, dammit!)