I have showdead turned on so see shadow banned comments.

What you're claiming is wrong and misleading. It's rare and almost always justified.

For the times it isn't, which I haven't seen for a few years, I've emailed those people where they've shown an email.

They usually say thanks, that other people have also emailed them and they'll contact the mod team.

i.e. there are plenty of long-term members of this site that keep an eye on shadow bans and we generally thintk it's working as intended.

I checked one out a couple of days ago, and literally 4 comments earlier dang had warned them that if they kept it up with the short, low-quality comments they'd probably end up shadow-banned.