Just had a thought - I’d imagine more people are scammed by “You have 3 viruses on computer” pop-ups than would be better off with a visible warning from macOS for background detections.
Perhaps apple made the (reasonable) decision to not alert people to background detection/remediations so as to not get users used to such alerts?
How about this alternative explanation: Apple is very concerned about its perception in public and doesn't want user to see that their OS has quite a malware issue.
A lot of Apple users still believe that macOS is superiors when it comes to security. But reality looks more like:
They often show a "Mac version" of those for MacOS users. It doesn't matter much that the warning doesn't exist in the system. They're not targeting people who know that.
Perhaps apple made the (reasonable) decision to not alert people to background detection/remediations so as to not get users used to such alerts?