There is absolutely no reason why the engine/steering/etc system is connected to the radio/phone/etc systems. None.
Of course there is. Multiple reasons really. Remote starting. Theft recovery. Accident reporting. Interconnectedness has many benefits... and risks.
“There is absolutely no reason why the engine/steering/etc system is connected to the radio/phone/etc systems. None.”
Automobile design contain embedded systems which are connected via an internal vehicle network for purposes of optimized control, diagnostics, maintenance.
Vehicle internal networks have lacked sufficient system security architecture until recent years.
Auto manufacturers recognize it’s a problem, and have formed a consortium along with the IEEE to address vehicle security standards.
Search on the subject for further reading and updates.
CANBUSS systems connect every electrical and electronic part on some vehicles. You can’t even change out the sound systems on some new vehicles without “bricking” the vehicle if you don’t have proprietary software to do so.
“There is absolutely no reason why the engine/steering/etc system is connected to the radio/phone/etc systems. None.”
Sure there is! The government might need access...for your safety, of course.