It is a bit odd that "monospace" in a mac browser gets you Courier/Courier New, because macOS has come standard with Menlo for ages and Monaco since the OS 9 days, both of which are excellent monospace fonts that are far and away better than either Courier. Even weirder, outside of browsers requesting a monospace font will get you Menlo.
Newer releases also have San Francisco Mono that it could use instead, which is even better since it's tuned for modern displays.
Apple is notorious for wanting to push people away from portable and easy-to-use web applications to non-portable, expensive to develop, and frequently worse mobile apps.
It’s more that they don’t put the high level of refinement into the web experience that they are famous for in their native (Mac/iOS) applications.
Though of course there are plenty of discontents with that. On balance I think the apps that ship with MacOS are much worse than their Windows counterparts. I think iOS on the iPad is truly superior but the settings app is dark pattern city, particularly the notification that never goes away about the Apple TV trial that is about to expire but actually expired years ago.
Newer releases also have San Francisco Mono that it could use instead, which is even better since it's tuned for modern displays.