CarPlay is a fantastic system because it keeps you off your phone.
But some of these new infotainment systems, and the complete lack of physical controls, are starting to feel extremely unsafe.
The passenger can use the phone if you want to be able to scroll through an artist's catalog, rearrange playlists, etc. CarPlay's UI is a quick way to access your current library.
Tinfoil hat time: CarPlay was created as a 4D regulatory chess move, because it enables users to continue interacting with their phones in a legislative environment where said action is otherwise illegal.
It would be hard to argue that it’s illegal to use the phone in a way that’s nearly identical to the way you interact with your vehicle controls.
That said, Car Play isn't a panacea for keeping me off my phone though, because some manufacturers have the ability to LIMIT what Car Play can show you.
Example - we have two vehicles for our 3 person household.
One is a 7 year old Kia EV, the other a nearly new Ford.
Ford has somehow limited apps like Music and Podcasts to show or give access to only a tiny subset of playlists and songs when the car is moving - exactly when you absolutely shouldn't pick up your phone.
So you pick up your phone because that thing that works in one car, doesn't work in the other - and it's the newer car and car play implementation that's more limiting.