Why are these costs so high?
IMO because of the endless government red tape that has been caused by environmental concerns. These combined with endless lawsuits brought by organizations such as greenpeace, raise the price of domestic production and infrastructure.
If the other oil producing nations were to face similar circumstances, our domestic oil would be more than economical. I do not see in the near future, any chance of an eco-terrorist telling any of the Saudi princes that they need to clean up their environment.
If we delay opening ANWR for too long, the infrastructure in nearby Prudhoe Bay will be deteriorated to the point of making the oil unrecoverable at $50 per bbl.