Always happy to have dialogue. What I'm about to say will likely offend, it's not meant to, it's just my opinion.
There isn't a single metric that I'm aware of that puts Canada and the US on par for the handling of the Coronavirus. But even ignoring the data, as that can be perverted by "the deep state" or foreign interference or even individual perceptions. If I look at how our populations/politicians are handling the Virus; from the beginning with the flip/flop narrative on the virus, the run on toilet paper, to the ongoing narrative/battles regarding masks, the nightly garbage (re: Coronavirus) that is spewed out of US politicians mouths (on both sides and seemingly at all levels of Gov't). America doesn't appear to be a country in control. That lack of control doesn't breed confidence. Combine that with data that supports the US trailing virtually every western country in its' response and you end up with the continued border closure.
Beyond the Coronavirus response, I have personally seen more disdain directed at Canada by Americans (both politicians and individuals) in the last 6 months, then the previous 40+ years, and very little of it is related to the border closure. I'm not the only one who has noticed this shift and when you combine the seeming instability with anger and an FU attitude regarding anything that doesn't put America first. Well, closing the border does seem like the safest option. I've heard a number of Canadians with similar sentiments.
So while the Virus alone may have been enough, in my opinion, to both close the border and then keep it closed. This bizarre level of angst that has been directed at Canada doesn't help, it only polarizes our population more and takes away less of our desire to see the border open.
I think this is all immensely sad and maybe I'm naive, but I always looked at the US and Canada as the closest two allies and friends, in the world. Now, I'm not so sure where we stand.