That said I will stick with using the headphone / aux input method as I mostly use it for stop / start delivery driving and it takes a while to re-read the USB directory info each time (apart from which most of the work van radios don't have a USB input anyway). I also keep a copy of my music on my phone which provides an even easier interface to browse and choose music to play.
I feel like you might be looking at this feature in the wrong way perhaps, or misunderstanding the way it functions.
In your described use case, as a start/stop delivery driver,
Car Adapter Mode could indeed be highly advantageous to you.
Car Adapter Mode automatically starts and stops playback based on detection of a power supply, if the car head unit in your vehicle is wired correctly (tied to the accessory rail in the vehicle wiring loom - as opposed to being constantly actively powered), and with a sufficient
Idle Poweroff duration (set this to something large-ish, like 30~60 minutes or so - this isn't particularly wasteful as the device is constantly powered when the vehicle is in use, and will not drain the battery in a properly wired vehicle loom), you should not need to interact with the device at all unless the idle poweroff duration has expired.
You would get in the vehicle when you start your day, start playback, and from that point onwards playback will stop and start on the device whenever power is detected (ie. keys in the ignition and on the accessory notch in the ignition barrel), but the device will still power off after the idle timeout duration has expired when power is disconnected from the device (ie. ignition off).
I find this particularly useful if you just like to set a large playlist on repeat shuffled. Get in the vehicle and interact with the device once in the morning to initiate playback, and then enjoy playback starting and stopping automagically whenever power is connected or disconnected (unless the idle timeout has been reached while the device is not actively powered).
This would be useful for anyone who spends a majority of their time in a vehicle making short stops frequently that require the vehicle to be stopped and started with equal frequency. Taxi drivers, couriers, postal workers, delivery drivers, etc. and so on.
I would stress that there is essentially no reason not to use this option, and every reason to do so.
It really does not matter in the slightest if the car head unit does not support USB direct connection, as this is not required for car mode to function at all. You could quite easily get exactly the same effect by continuing to use an axillary cable as you are already, but supplying power from a USB car cigarette lighter adapter. If of course the car cigarette lighter is properly wired to the vehicles accessory rail, and not actively powered, like they seem to be in many older vehicles.
Even if that is the case, it is foolishly easy to correct wiring mistakes like this, or to just add another power supply port tied to the accessory rail. Automotive wiring looms are foolishly simple.
[Saint]