I saw that post and my thought was that those 79% are not Tesla owners.
I believe Apple CarPlay is a workaround for oem to provide a decent UI experience in their cars as they don’t focus on that (UI) and prefer to delegate to Apple or Google.
I saw it for myself and read regular complains about CarPlay that I just don’t have with the Tesla interface.

Tesla has focused since day one and is still aiming at a great UI experience.
But it is a work in progress.