A smaller country with low diversity results in more uniform opinions, I suppose?

But, comparing Norway to the U.S.A. would be odd. From over here, the U.S.A. can be compared to the E.U., in which case the comparison should be between American states and European countries.

Specifically for Norway, it would be like a state in the middle of the U.S.A. that never actually became part of the union, but with really good ties with everyone regardless.

What is the largest contemporary social democratic government? Sweden is about twice the size of Norway. Is there evidence that it's getting scale benefits out of that?

One of the downsides is that a larger system collects more money and becomes a much more ripe target for individuals looking to corrupt it.