The culture of Japan has a very high hygiene element which skews the result.
I agree with 90% of what you posted, especially about the Japanese culture.
Where we differ is on the effectiveness of the mask for three reasons, one mostly overlooked.
The first is that it does reduce the distance the crud emitted from your mouth travels.
Second the mask keeps you from putting your fingers in your nose or mouth and stops you from using your mouth as a third hand.
Unfortunately there is no third. My debate professor in college told me that you should always cite three things to make your point.
Ken