I'll point you to Hong Kong, Singapore, Shanghai, and Tokyo as counterexamples. All of those cities are 3-7x denser than LA, more populous, and culturally multigenerational.
I think it's quite clear to anyone who's been paying attention at this point that behavior has more to do with containment than anything else. The US and perhaps LA in particular for some reason or another is unwilling or unable to implement the same behavioral safety measures of other countries and cultures.
Mask wearing is the obvious one. If you go to any of those 4 cities I mentioned, 100% of individuals in public are masked, whether indoors or outdoors. 6ft social distance is very strictly followed with public shaming for those that take off their masks or do not follow social distancing guidelines in public.