It might also just be a reflection of the distribution of medals available - Norway has dominated in the cross country skiing based events, but Germany dominates in the sliding events. Between biathlon,cross country skiing and nordic combined there are 26 disciplines, but luge + skeleton + bobsleigh have only 10 between them.
The "two medals" is a quirk of one particular way of displaying medal tables.
https://olympics.com/beijing-2022/olympic-games/en/results/a...
- Number of medals per discipline - Competition from other countries in each discipline - Cultural factors. For example, cross country skiing is not only a sport, it is also a leasure activity in Norway, similar to hiking. - An accessible sport have an easier time to get many participants. Most of Norway gets snow in winter and access to nature is not particularily restricted. I don't know for a fact but I imagine in the US you are not equally allowed to ski on someone else's property? - Financial means. Goes without saying but Norway can afford supporting youth and elite skiers on many levels.
Also, the countries you mention are big, but how many people actually live close enough to a ski resort (or similar) to actually matter? Is it significantly different from say Austria or Switzerland, which are small, but where a much bigger proportion of the population can actually train for winter sports?