The oil industry, as rich as it is, is probably subsidized by the taxpayers. Much of the income from it goes to invisible bank accounts in the Caymans (etc) and isn't taxed. The citizens tend to be the ones to really foot the bill for oil spills, the refineries aren't being maintained, etc, etc, etc. The real cost of production in this country tends to be a lot higher than what you think you see.
Not sure I'd agree that the money is heading off-shore. As most of the oil companies are traded publicly and sooner or later need to bring the $$ into the accounting system.
The U.S. is tough on hte petroleum industry in a few ways. We make it retool and reformulate gas for various areas. You cannot sell the same gas all over.
We do not allow refineries to be built. The last refiniery built in the U.S. was built decades ago. NIMBY has become BANANA (Build Absolutely Nothing Anywhere Near Anything).