> "and the only way to listen to music while driving is if you bring along your phone and a Bluetooth speaker"

Why not make a physical connection (power/network) and define a form factor for entertainment system with or without screen and speakers and let other companies design something to fit the space available. I don't understand why no one does this instead of selling cars full of crappy software that can't be upgraded.

Double DIN already exists with fairly standard plugs in the back

That's what cars always used to have. Made them easily stealable though.