The big reason why DAB did not gain interest two decades ago is that the "internationally recognized" DAB band in the US had long ago been given to military use.
Quite so, but a pretty lame excuse at the time. Since the rest of the world seems to have adopted the same frequencies for DAB use, the US military would find them quite inhospitable anywhere outside of the US. From all I've been able to tell, the military doesn't even use those frequencies, although they are reserved for them. DAB frequencies run from approximately 174 MHz to 239 MHz. Most military frequencies start at 242 MHz and go up. The very idea that adopting DAB in the US would level the playing field between flame thrower stations and under-powered Class A's was repugnant to many larger broadcasters. As a result, the drum beat of "The military needs those frequencies" was amplified by NAB and others. It was similar to the way the anti-LPFM crusades were launched. As one poster on an earlier version of this board said, "If they are listening to one of 'those' stations, it means they aren't listening to my station, and I don't like that."
Things are different in Norway. It is a classic Scandinavian "nanny state". They will move to DAB, like it or not.
I was wondering if anyone here has actually visited Norway? I have. It is a lovely place in the summer with a friendly and well educated population that is mostly clustered along the coast line. You can keep it in the winter. Whenever you go, be sure to bring money. Lots of money. It is a very expensive place to visit.
The population is anything but ethnically diverse, and they like it that way. Norwegians enjoy a very high standard of living, mainly because they have a very small population (about 5 million people}. That is smaller than the population of many major US metro areas. Their government and its resulting life style is supplemented by income from North Sea oil, which pays a lot of bills. They also have some of the highest taxes anywhere. When I last visited, Oslo had the distinction of being the most expensive city in the world, edging out Tokyo. Because of their small population and relative wealth, a lot of things work for them that would not work in the United States.