The worst cases are mostly small, often serving low-density rural areas—in Ontario, Chesley, Clinton, and Wingham are a few names I could find quickly that have had such severe staff shortages they've had to reduce ER hours or close temporarily (they're fairly close together, in Bruce and Huron counties, so if one of them closes the patients that would have gone to that one probably go to the others instead and make the wait times there worse). The hospitals with long wait times merely have, say, two doctors handling the ER patients where they should have three.

One part of the problem is that the doctors and nurses we do still have tend to migrate toward the larger metro areas, just like people in other lines of work. That leaves hospitals in small- to medium-sized urban areas even more understaffed, sometimes to the point that not even one doctor or RN can take a vacation without causing truly excessive wait times even if a shutdown can be avoided. In Ontario, western areas seem most affected, but the northern part of the province has been dealing with chronic medical understaffing for decades already, not just since COVID.