Those aren't silently dropped though, are they? The sending server is notified I think.

Yeah, there's a lot of spam out there. My employer's spam filtering software used to send out weekly statistics telling us what percentage of incoming e-mails (across the entire company) were spam. The spam percentage was remarkably constant from week to week: about 90% of all incoming e-mail was spam!

Who cares? The only things that make it into my spam folder are obvious spam. Meanwhile, messages from people I know personally aren't even delivered at all. There is no way to characterize this as reasonable or even acceptable. Google is using metrics that are not related to whether an email should be delivered.

They need to tune whatever they're doing down to the point that legitimate personal communication at least shows up in the spam folder. If a lot more spam shows up in the spam folder too, so what? A spam folder that contains mostly spam and also some misclassified personal messages is significantly better than a spam folder that contains nothing but spam because it automatically dropped your misclassified personal messages.

I deliberately set GMail to the lowest level of spam filtering they'll allow, and still only receive a couple of spam messages per month at most. They need to adjust their levels.

I run my own mail server and never silently drop any messages. I also have a catcha-all inbox and my primary email address is available publicly in many places (my website, git repos, bug trackers, ...). The amount of spam is really not that bad.