You're right, however, CarPlay is already a very recent development. Bluetooth seems like quite a major omission, especially when you consider that it has been an established technology in cars since at least the turn of the millennium.
Thankfully that doesn't bug me so much, because I tend to want to charge my phone when I drive anyway.
It's not a restriction. Apple simply hasn't built out a fully featured third party SDK for CarPlay yet. It's impossible to build a maps app using the currently available third party CarPlay APIs.
Thankfully that doesn't bug me so much, because I tend to want to charge my phone when I drive anyway.