CarPlay doesn’t just mirror the iPhone screen. It’s drawn on the car screen by the app. It requires the app to be updated to support it.
Exactly. And even the whole idea of actually drawing things to the screen is actually a new concept. I don't know why most people haven't noticed what CarPlay (so far) is and isn't for third party apps.
Look at all your third party apps on your CarPlay home screen. They're all simple audio players and unlike the actual software on your phone, they all have identical UIs which doesn't match the app, rather it's essentially a carbon copy of Apple's Music app UI. In a "Now Playing" view they're allowed to show a play/pause and two skip-x-seconds back/forward buttons or previous/next track buttons. They're allowed to show two lines of titles (such as song title + artist & album). A couple of buttons for repeat and shuffle if desired. And they can show a bar showing position in the track, and a cover art that will be zoomed, blurred and darkened to be barely recognizable.
They also can show a couple of tabs atop a table view that you use to select a thing to play, like so:
However the above is literally all anyone has ever had APIs to do. If Waze and anyone else is allowed to
actually draw to the screen now, it's a whole different API that is brand new. Apple hasn't, as someone suggested, been blocking apps from doing something, they just haven't given apps any tools at all (other than audio apps) to do anything with this external screen.