(a) other countries exist, and
(b) New York and other American cities could learn things about mass transit from them
Has pretty broad applicability so I hope folks dig in on this.
nytimes.com/2020/08/02/nyr…
Obvious robustness check: Are high ridership cities in general Covid hotspots?
That doesn't even vaguely resemble a list of the cities with the worst outbreaks.
The observed pattern of Covid-19 is the opposite of that. I wouldn't try to claim that low transit usage causes Covid outbreaks — it's just that masks work.
¯\_(ツ)_/¯