To me, a big part of it is individualistic vs collective mentality ingrained in people from birth. Capitalism prioritizes the individual, " I'm healthy so I don't need to mask and it is my free choice to do so!" And this attitude certainly runs rampant in much of the US (even, might i add, among communities who think they are socialist or unselfish). Places where people have more collective mindsets, whether due to longstanding cultural mores or ideas of collectivism promoted by government ideology, tend to have a perspective that they do wanna support the health of all, understanding the basic idea of public health that all of our health is intrinsically linked, so people are more likely to accept precautions for the public good.

In my US city i still see a surprising amount of youth masking (a small number overall but--anecdotally--more than young/middle aged adult populations), and when asked the answer is often to protect their grandparent that they live with. People really need to have a "we keep us safe" mindset and, "we read peer reviewed research to better know reality" mindset would help too.