Bluetooth deafult to "iPhone"?

Whenever I enter my vehicle and start it up, the phone auto-pairs. Then, it decides that my BT device should where ALL audio is directed all of the time.

I have yet to own or drive (rentals) a vehicle that properly receives audible alerts from a phone and plays them through the audio system (unless you're on the phone). So, why does the BT system in even the current incantation of iOS still insist of trying to use my audio system for audible alerts?

The phone can (and does) "remember" the last source that was used when placing or answering a call, and will sometimes leave you wondering why you can't hear the person on the other end when it directs the call audio to the phone. Why can't we at least have the same sort of thing for the audible alerts? I don't EVER want audible alerts to go from the phone to the audio system (unless I'm on a call, and even then it isn't a requirement), and every head unit out there supports a "Connect" sort of option when you want to use your phone as an audio source for music or streaming.

Is there a way to achieve the functionality I'm looking for? I want AirPlay to default to the iPhone, ALWAYS.

If not, is there any plan to at least give the user an option to CHOOSE a default? Or to remember the previous setting?