Another reason is that nearly everyone wears masks. And there's plenty of space, so everyone can keep their distance.
(We're lucky that we have an apartment to go to. Otherwise we'd been standing outside the airport like hundreds of other travelers right now.)
A privately owned railway in Japan called the Choshi Electric Railway operates on only four miles of tracks. Business is bad, so the company is trying to monetize in part by selling rocks from under the tracks. In cans! Why, Japan? Why?