[mikekchar]

According to Wikipedia, the original author does not consider COVID-19 a black swan event, so I think you must be right. However, while we know a pandemic will occur, we don't know when. Neither do we necessarily know ahead of time what measures are appropriate to take to mitigate the risk.

The aspect of the Black Swan theory where you point to the data after the fact and say, "We should have known" is very similar. For example, countries that experienced SARS and MERS where very much more prepared for COVID-19. Other countries which didn't have many problems did not prepare. This is because they didn't realise that they should prepare. For them COVID-19 was out of the blue -- a complete shock. Of course, we should have looked at the original data and if we had, we could have improved the outcomes. But we didn't have that experience and we didn't know when to expect a large problem.

The Tohoku earthquake in Japan in 2011 was similar. Earthquakes of that size hit Japan about once in 1000 years. We know it will happen. We don't know when. We don't know if it will happen in our generation. Should we prepare for it. In hindsight, yes, of course. At the time, it was a shock.

Is that a black swan event? I don't know. However, I don't think we need to have much of a distinction. Even if we should know, the fact that we don't know is all that matters. It is still a surprise.