My friend in Sweden tells me they had constant behaviors over time, they never at any point "changed" to being more careful, they were careful from the get go.
That is one person of course.
I tend to doubt folks saw bad numbers and tightened up on that overall, I see evidence to the contrary.
And the theory is that folks have immunity/resistance from a similar corona virus in the past in large numbers.
Cincy, I can tell you that just from your own posts, it seems like your behavior became more lax as things started to open up, especially because Georgia's numbers weren't spiking, and then tightened as Georgia's numbers started to go up.
Would that be accurate?
I'll bet if we polled most of the posters here, a good number would say that during May when we were in a lull in cases and things were reopening, they slowly eased their behavior, and then when cases started spiking hard in June/July they tightened. I know I did.
And I'm not saying the theory that there is some immunity, perhaps from the variants of the common cold, that might be helping some people out. I consider it conjecture rather than something that has the weight of evidence behind it, of course. But I'm willing to admit that it's possible, and perhaps as the science becomes more clear, we'll find out it was there all along.
What I'm saying is this...
When cases started spiking in the US, but deaths didn't, there were a whole lot of conjectures as to why. Maybe it was because we had better treatments. Maybe it was the different age cohort. Maybe it was because the virus had mutated to be less deadly. Some of us said "hey guys, think about the lag time, maybe we're getting complacent", and lo and behold, 3-4 weeks after cases spiked we saw a significant national upturn in deaths.
Now we went through a major spike of cases (which wouldn't make a ton of sense if we had widespread immunity) after reopening and now cases are dropping despite limited official changes to gov't policy on reopening. People throw out ideas like "oh, maybe immunity is more widespread than we thought" because we didn't change policy, but those of us who follow the human side of this believe that individual behavior DID change due to the spike in cases. And that it's a lot easier to explain a drop in cases based on behavior than it is on the idea that some completely unknown and unproven immunity exists.
So... You might be right. But I'm going to withhold my hope/believe in that theory until we see some more evidence than looking at the curves and speculating.