Meanwhile, a ticket to Glasgow during the same period is only $616. And you have to fly over Iceland to get there. In the other direction, I can get to Anchorage for only $503, though it requires an extra stop. For the same $616 it takes to reach Glasgow, I can get a one-hopper to Anchorage.
I guess it comes down to how many people want to go someplace. Lots of people want to go to Scotland and Alaska, at least compared to how many want to go to Iceland.