I use android auto every day too, and it absolutely does those things.

When you turn your headlights on (I.e.when it’s dark) the android auto display goes from light mode (so you can see it even in blaring sunshine and wearing sunglasses) to dark mode (so it doesn’t blind you when it’s dark). It doesn’t do this via magic, it does it because the car sends that information to your phone.

Android auto also will not let you perform some functions while driving. It does this by detecting your handbrake. This is a legal requirement in many jurisdictions.

There’s also more minor things like the car telling the phone whether it’s RHD or LHD and altering the UI accordingly.

So respectfully, you are wrong. Not only is it useful, but it’s sometimes a legal requirement. And Android Auto already uses data sent by the car.

That’s why alternative solutions don’t exist.