Should be "Why gas everywhere but the US is so expensive". The base price is set organically in the market, the price including tax is a result of external government meddling.
The gas tax bothers me less than any other tax. The roads are inevitably paid through taxes--I doubt a libertarian scheme exists that could actually privatize them. In addition, there's a non-trivial chance that the natural price of gas will be very, very high in the future. Taxing it now heads off any serious disruptions caused by that.
>I doubt a libertarian scheme exists that could actually privatize them.
Private highways have been successful over the last several hundred years. The earliest highways in the United States were built without tax dollars. If you can't conceive of how roads could be privatized, I would say you lack imagination.
I agree that the gas tax bothers me less than other taxes, since it tends to be paying for use of the roads. However, if we were to tax it as much as other countries I would be offended.