Because of market manipulation and oil speculation.
In other words, Wall Street has a lot to do with the spike in gas prices. Via ThinkProgress, here are some progressive congressmen who would like to do something about it:
REP. PETE DEFAZIO (D-OR): A member of the Commodity Futures Trading Commission said…a significant portion of what we’re paying here is due the speculation, I’m going to ask him if I can publically release his letter. … And this is a member of the commission saying this has got to stop.
REP. BRAD MILLER (D-NC): There is also, obviously, a lot of manipulation. It’s a little hard to detect it. But there actually been articles in the last couple weeks talking about the Koch Brothers, in addition to all their other good works, have been involved in oil speculation over the years. So there is an an international market that is subject to manipulation.
REP. CHELLIE PINGREE (D-ME): I still fell like speculation drives up the prices. And I would he happy to see us do more about that.
I’m rather ambivalent about gas prices. I actually believe gas should be more expensive, but more expensive by way of a gas tax — the revenues funneled into green energy R&D. But high gas prices for the sake of Wall Street speculation ought to be banned and violators punished.