There was a almost total shutdown after 9/11. After some time business was back to normal.
After the initial shock things quickly recovered, but the major difference here is that people weren’t dying from outbreaks of 9/11 in towns and cities throughout the world. Even New York wasn’t locked down in the days following the attacks, let alone the rest of the world. The daily death toll from COVID-19 is probably exceeding the total death toll from 9/11 with no end in sight.
The damage is much more widespread and extensive, the recovery will take years.