I think this is a failure of imagination on the part of the author. Norway is, on a whole, much more rural; a large portion of the population lives in small towns and villages in areas with difficult terrain (think fjords), where public transport beyond a bus is impractical due to population densities.
The public transport in Oslo and Bergen are fantastic - Norway’s only two large cities. Keeping in mind that over a quarter of the population of the entire country lives in these two, it’s not as bad as it sounds.