I always found that Apple had pretty mediocre software qualify, it's always been a very strong hardware company first and foremost.

They have great kernel, drivers and low level engineering but the stack above that has a lot of questionable stuff.

I only partly agree with this. The answer is maddeningly more complicated.

Some parts of their software stack -- higher up than the kernel -- are actually pretty great. There's a lot of realy brilliant stuff in their system frameworks, and in SwiftUI, Cocoa, and UIKit. I've been using Linux at home recently, and I find myself missing some of it.

But, on the flip side, suddenly you hid maddening bugs, crashes, or terrible developer-experience papercuts. And, of course, there's the App Store, which is just evil. For my next app I'm just going to go Notarization only, and see how that goes...

The comment above is on to something. I find CarPlay to much more valuable and much more of a lock in to the iPhone than Siri. I do not think I could ever go back to using the infotainment systems that ship with cars. So makes sense why they might prioritize over Siri. And in the context of CarPlay, the simplicity of Siri is nice. I really only need it to execute a few simple commands like looking up directions, making calls, reading / sending texts, playing a podcast, etc.

I don't dispute that, but Apple made its business on the premise of being the best in the business in terms of UX. Note though that you can have great UX powered by mediocre software, so those aren't mutually exclusive.