The very normalization of antivirus on Windows is a Windows problem. For better or worse, Mac users simply don't think about AV.

Like you say: "for better or worse".

FWIW, I haven't ran antivirus software on Windows (other than the included Defender, but that's not something I think about) in literally decades.

I think letting certain software thrive which just blatantly disregards your own certification and validation processes is exactly Windows problem. Some developer(s) paid 600$ and emailed their passport to Microsoft affiliates to get rid of that "SmartScreen" warning, do they have to pay and email their passport copy to AVG as well so their application can be ran without uploading step and needing to wait few hours of "examination"?

What are you saying here, though? That Microsoft should have the monopoly on deciding what software is safe and what is not?

Windows historically allowed a dire situation with security, so no-one really freaking knows what software is safe and what not. Even monopoly they have on deciding what software is safe and what is not (extended validation certification procedure) is not helping anyone, because anyone can circumvent it with photoshop and 10$

Are you saying Microsoft shouldn't care about making a secure system and they can just outsource the subject to a third company which will upload .exe to their server and tell user to wait few hours before it can be launched?