While it might be hard to pick up from most news coverage, oil companies are not actually formed for the purpose of coating the oceans with petrospills. Nobody sits around the offices of Shell or BP and says "Bob, draw me up a memo for how we can have a new oil spill next week." Believe it or not, they try as hard as they can to avoid those.
As a matter of fact, they hate them even worse than Greenpeace does. See, whereas your typical filthy hippie looks at events in the Gulf and starts crying because they see all the poor fishies and birdies getting oil on them, your typical BP exec looks at the events in the Gulf and starts crying because he sees a giant freaking hose spraying money like a broken water main.
Plus, they'll need to pay to clean the giant money slick up.
And then they'll get sued.
That is a better incentive to not spill the stuff than any number of picket signs.