Apple isn’t forcing anything. They don’t have exclusive contacts. Almost every car with CarPlay supports Android Auto.
Customers are just demanding it.
By comparison, nothing (not even Google) is stopping Apple from producing CarPlay for Android. All the APIs are there. They could even distribute it in the Play store.
Compare the PhoneLink capabilities between iPhone and Android, vs the macOS integration Apple offers iOS.
I was not talking about the infotainment OS. No one has an Apple OS running on a car so I don’t know how they could dominate the market.
It happily allows CarPlay from my iPhone.
CarPlay is (very roughly) the phone pushing video to the car's head unit like it's an external monitor (with a UI tailored for the size/location/usage of a typical car display).