I would argue that the quality of governance of those countries and the strength of their economies relative to the US dramatically outweigh looking at size alo

I would argue that the quality of governance of those countries and the strength of their economies relative to the US dramatically outweigh looking at size alone. Size makes things easier. The more scale the more predictable the costs. We have a single payer system for everyone 65+, because we had the political will to do it, and it remains funded and functional because it is an important and powerful political bloc. A lot of people make a lot of money from the dysfunction of the system for everyone else and they fight tooth and nail to keep that gravy train flowing.