The thing is, we ramped up testing at the same time schools and universities went back, it would be interesting to see % people tested during September by age vs say July and August..... the sceptic in me says a lot more school age people are being tested so stands to reason that the positive cases will be higher for that populous!
I know of 3 school "bubbles" that have burst and the group sent home for 14 days after 1 child in each bubble tested positive. In all 3 instances not a single one of the other children in the bubble presented any symptoms or needed tested, which would suggest is ISNT being spread in schools and more likely being taken into schools by children who have caught it from family members/elsewhere.
There are just so many variables and we've not had any periods of testing where the focus of testing were the same groups, so we simply can't compare the data!
Example, look at how many deaths there were in April as a % of positive tests, it was massively higher than now but of course it would be, in April we were only testing care settings and hospital admissions so only the most severe cases! All this tells me is that Covid was just as rife back in April as it is now, we just didn't know about it because we weren't testing.
Also I agree that maybe there is some logic about masks and viral load, why is it that cases are high now but deaths and hospital admissions aren't as high??