At $5 a gallon, gas is cheap. Considering that an Odwalla drink is 16 ounces (about an eighth of a gallon) costs $3 and a 12 ounce mocha costs $4, why shouldn't gas cost more considering it required finding the oil, pumping it out of the ground, shipping it, refining it and then distributing it to gas stations?
That's a lot of energy expended to get to your pump. Procuring oil requires invading foreign countries and bombing them into compliance until we can bleed them dry of black gold. Oil supports the worse regimes in the world: Venezuela, Iran, Saudi Arabia, United Arab Emirates, Angola, Libya and the list goes on. Oil allows those in power to stay there, while depriving its citizenry of basic rights. In America, if we dislike where our country is going, we can forgo paying taxes and eventually stop government spending. Most OPEC (Organization of Petroleum Exporting Countries) take all the revenue from oil and offer their citizens welfare to not upset the balance.
Next time you fill up remind yourself, "Gas is cheap," because there are millions of people living under oppression, poverty and totalitarian governments so that our $20 goes a little farther.