Good questions. Inexpert opinion follows. The one thing I do know is that profit from refinery operations is low. Companies don't like to make big investments with low profit margins as a result. I'd opine that the risks posed by class-action NIMBY litigation also dampen enthusiasm for investment here. Add to that the demonstrable threat and expensibe risk of ever-changing government regulatory changes and I'd say that companies have better (safer, more profitable) places to put their capital investments. Finally, I believe (but do not know) that the big companies are operating as an oligopoly and skewing free market behaviour in their favor. I say that oil and other major industries (Hollywood, sugar, etc.) each have their different political reps in Washington providing air cover for their "modifications" of free market behaviour.

-p