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.
The CAN Bus will intercept things like wheel position, accelerator postition, gear, etc. and feed it to the actual implements (steering control, throttle, tranny). Yeah - you can really hose someone up by hacking into the CAN Bus. But we all like the nice power everything and we have to have our connectivity...