Their general use of masks and gloves before the pandemic in high density urban areas is instantly noticeable. It's not 5%, it is closer to 50%.
I saw punks. Literal goth punks, with the boots and the tats and the piercings and the black clothes and the mohawks wear masks.
Before the pandemic. Not during. Before.
In America you have Karens screaming in the face of shop attendants about their "rights" and how they have a "medical condition" that prevents them wearing a mask.
So, yeah. I don't think it's a mystery that Japan did better than the US.