We don’t know that masks are ‘working’ in Japan, Korea, and Taiwan,
We may know that they are having a lower mortality rate due to COVID, but that may be due to some other factor (e.g., less obesity in those countries).
They aren’t just having lower mortality rates, they are having lower infection rates. This in spite of being much more densely populated, and reliant on public transportation.
We don’t know that masks are ‘working’ in Japan, Korea, and Taiwan,
We may know that they are having a lower mortality rate due to COVID, but that may be due to some other factor (e.g., less obesity in those countries).
Those countries don't just have a lower mortality rate. They have many fewer cases for their population than the US. America has 7,789 cases per million while South Korea has 247 cases per million, Japan has 144 cases per million, and Taiwan has just 19 cases per million. And the citizens of these countries all live cheek by jowl in dense urban centers where social distancing is impossible in many cases. I'd say their masking policy is working out a lot better for them than our masks-mostly-optional policy is for us.
https://www.worldometers.info/coronavirus/#countries