I believe that the reason for higher prices for gasoline outside the United States is lack of availability. The United States is still a major producer of oil.
The U.S. is not in the top ten producers which are Venezuela, Saudi Arabia, Canada, Iran, Iraq, Kuwait, UAE, Russia, Libya and Nigeria.
My country, Australia, produces more than enough for our own needs, yet we still pay double the price in the U.S.
And in a poor country like Madagascar, with an average per capita income of $260 p.a., they pay the same price as in Australia. Taxi drivers need to have a down payment which is collected from the passenger near the start of a journey in order to purchase enough for the journey.