Again, because of the incentives, the vast majority of them being delivered to the spam folder still means a significant chunk of e-mail that does not go in to the spam folder is spam, and that a bunch of e-mail that is not spam ends up there.
> the systemic realities are nonetheless a very real problem.
If you have data/industry experience in support of this, I am genuinely interested to hear about it, otherwise it seems like a case of my anecdote against your anecdote. It is not clear to me as a layperson that spam misclassification is indeed that big of a problem.
In terms of industry data, spam filters are generally seen as effective with about 99% effective, though Google has claimed they've achieved about 99.9% efficacy in the last few years, though there's some question as to how they are measuring that.
The problem is, even at 99.9% efficacy, with around 50% of all e-mail being spam (that number used to be much higher, and there's some question as to whether the drop to 50% is a trend or a reflection of failures to detect/identify), that's still a lot of spam getting through.
