Think of it this way. They (the government) tax motor fuel, which society needs second only to water, the way they price alcohol and tobacco. They load it up with multiple different taxes (sales taxes, cap-and-trade taxes, energy taxes, weight taxes, road-use taxes), and in some places the tax burden is higher than the price of the product.

They do this to discourage you from driving your car, so they can control your mobility. It hurts the lower-earning folks the most, but they have to go to work, so they pay. And they scrimp on other things.