It’s exaggerated but only slightly. Some of the worst messes I’ve seen were people who should have known better just blindly pasting google search results because they didn’t have time to do it right.

More developers than sysadmins but definitely not exclusively so. Never underestimate the degree to which people are rushing or not questioning whether their initial diagnosis was correct.

I would add that these kinds of "Normal users click accept/next" are how "offers" on software gets installed.

Case in point: uTorrent. Download and "install". You will, generally, get 2 screens that install junk. On one screen you can click "Decline". On another, you can click "Skip". These screens are between all the normal "which folder", "do you accept" and "thank you" screens.

Case in point: Adobe Reader... download it from their website WITHOUT unchecking the "Optional Offers". You then have a Reader with Benefits.

I consider myself "trained" and "knowledgeable" and I occasionally get bit by these... sidecars... included with desired software.

I have no faith that 95% of people know how to sidestep these "landmines". Decline? that means "don't install". Skip? Why would I skip an important part of the installation.

The problem with most of your examples is that either they're not dialogs ("unclick optional offers"), or they are expected dialogs (you expect during installation dialogs that ask you this-and-that, and you knowingly triggered the installation, so you mistakenly/casually click the wrong button). They are dark patterns, that first train you to click "next-next-next" then present you with an "offer" where you're also expected to click "next".

The system security dialogs like the "permissions" dialogs are not like that - I even read the Android permissions dialog (though I realize most people don't, I still think a sizeable chunk of people do, and thus I considered the original claim - that nobody does, not even developers/dev-ops - to be hyperbolic).

What about the High Sierra notification itself? The only options are "install" and "details"

I've been burned enough by bad installers that I go to ninite for any software like that.

If 1% of the population reads even half of their dialog boxes I'd be amazed.