A big problem in North America is that people's baseline health is poor compared to Scandanavians' and just about everyone else, in the First World anyway.
Yeah - baseline helth level is cited as a key difference. But in general, especially in the Nordics, the population has a relatively high level of trust in the government, various conspiray theories have very low take-up (we do have our share, but it insignificant). For the same reason the vaccination rates are very high, among the highest in the world, without really any consequences for yourself if you for some reason didn't want to get it. There is a small exception for health professional working with at-risk patient, but that's the only I know of.
The political landscape is largely consensus-driven, the entire public administraion outside elected represenatives in parlement is non-political (it doesn't change after elections) and the population is relatively well-informed. One thing, however our "CDC" discovered was how difficult it was to get information out to certain immigrant minorities, but they somewhat figured it out by going via mosques, community authority figures etc. However, if you break down hospitalizations by birth country there are massive differences with the immigrant population, mainly from the Middle East and Africa strongly over-represented. Same with eastern european immigrants, covid has taken a pretty serious tall in large parts of Eastern Europe and the vaccination rates are shockingly low.
When Australia suddenly got hold of a lot of doses back then it was mainly due to eastern EU contries cancelling their share of the available doses as they quickly ran out of arms to put them in. Compared to the 28 months in US life expecancy it was 27 in Poland and 43 in Bulgaria.
So all inn all the talk about population density etc might be far less relevant than one should assume beforehand. Culture, public health and society in general appears to matter a lot more.