I was about to say this. Also, in Scandinavia the salaries _have_ indeed kept pace with increases in productivity. In Norway, you can earn a decent living as a checkout clerk. It seems as if the business owners here have actually passed on most of the savings to their workers. I'm pretty sure this is exclusively a cultural phenomenon - a sense of solidarity and cooperation which the larger part of US culture does not have. (I'm not meaning to bash the United States here, but this view is compounded by the fact that American employee-employer relationships seem a lot more antagonistic and imbalanced).

There are also less super-rich people here since people are overall taxed more. The oil industry also adds to the general income level, but this doesn't explain the entire effect. I'm pretty sure the same can be observed, in Sweden and Finland.