Earlier quoted context omitted.
Why exactly would be concerning? You need to physically plug cables in the car you yourself own. If anything, every access to hardware you own SHOULD be this easy.
Well, not exactly. Once you have plugged this device into your can, it can be hacked. It's just a phone after all, and it has normal wireless connection options available.
So the driver can still regain control from a hacked device by deactivating cruise control, which s/he can do by moving the steering wheel or pressing one of the pedals.