Ummmm....... it took a good 2 to 3 years before it started showing up in cars after Apple announced it. It might be plug and play in Apples eyes but working with Apple I can guarantee there are a whole bunch of stipulations that must be followed to get it working and in this case it's Apple's way or no way so it's up to the automakers to make their systems work with it not the other way around.
I've had many arguments with Apple about integrations etc. and every time the expectation is we have to adapt, not them