CarPlay is a thing because carmakers just can't seem to make a decent "radio" with a touchscreen no matter how they try. It would be nice to see a business school case study that reveals why.
And then people still expect to connect their phones to the car, for calls/reading texts etc, so you still have to support that in some way... and people will expect that to play nice with the audio playback features (calls pause/unpause music, etc)
Since we're already supporting a phone connection, then it just makes life easier to bring your own experience. The auto maker supplies the interface, you bring your own apps, data plan, etc via carplay/android auto.
Personally, I find it's a huge step forward to whatever OEMs make in house which aren't updated/obsolete in a few years.
But CarPlay is 100x worse than Android Auto, even though Apple is supposed to excel at UI and UX, this was the point I was trying to make, not that car makers such at UI/UX.
Anything on top of that would just be extras, but something basic like that should work at least. Which it does on Android Auto, but not on CarPlay.