CarPlay and Android Auto aren't popular because they're good, per se. They're popular because they're good enough compared to the status quo ante, which was a sea of craptastic infotainment systems.

What does “not a good system in an objective sense” even mean? In what objective measures do you see it fail in?

I and basically everyone I know love it because it and android auto are made by actual UI/UX designers that aren’t embedded systems engineers- resulting in an infotainment screen that isn’t a complete and utter piece of shit, and has actual functionality. I use my phone for everything in my car anyways, especially navigation, which historically is not included in a cars infotainment system without subscription and/or vendor lock. In that one singular regard, CarPlay is literally infinity percent better than every single built in infotainment system, because I can use my fucking cars built in screen instead of my tiny phone display to navigate using software that is infinitely more well made than whatever shit is on my cars native system (a brief note: my angry tone is not directed at you or your lack of agreement with my opinion, but at how awful I perceived the car infotainment systems of yore to be. God they were useless.)

For every objective measure I can come up with in my head and not type out, it passes with flying colors compared to the alternative- so I’d love to know where your perception differs.