[BostonCard]

That is probably the biggest reason.  Another reason is that New York's peak occurred early in the pandemic when we had a piss poor testing regime, so a lot of people with COVID-19 never got tested, so we vastly underestimated (probably by at least an order of magnitude) the number of infected people in New York, thus overestimating the case fatality rate.  The wave in California seems to be cresting now, and while testing is still pretty bad, we are catching a greater share of the people with COVID-19, so we are underestimating the number of infected by a lower margin, making the case fatality rate a lower overestimate.

BC

[BostonCard]

That is probably the biggest reason.  Another reason is that New York's peak occurred early in the pandemic when we had a piss poor testing regime, so a lot of people with COVID-19 never got tested, so we vastly underestimated (probably by at least an order of magnitude) the number of infected people in New York, thus overestimating the case fatality rate.  The wave in California seems to be cresting now, and while testing is still pretty bad, we are catching a greater share of the people with COVID-19, so we are underestimating the number of infected by a lower margin, making the case fatality rate a lower overestimate.

BC