While I absolutely agree these inconsistencies are completely against the Mac OS philosophy, it's hard to not acknowledge how old the codebase must be starting to be, 20 years down the road.

Windows has the same issues, where you'll see stuff dating back to the NT days in the Control Panel.

I can't even begin to imagine how many different internal UI frameworks the Mac OS developers need to juggle now, compared to when Aqua looked as fresh as iOS 7 did at launch.

Apparently, Apple had planned to completely scrap their computers before the 180° decision to move to M1 and cater to pro users again, so one isn't left wondering as to why Mac OS is this way when iOS is much more consistent. It's likely we won't ever see a new computer OS ever again, similarly to why the web seems to have settled on being a Blink/WebKit platform.

Is it a shame? Absolutely. But it's going to be impossible to convince an entire sales team to get their developers to fix UI inconsistencies and rewrite every nook and cranny in the system to use AppKit, instead of working on marketable features that move parts of Mac OS to parity with iOS.