People get angry at the self-checkout for telling them to please be sure to take all of their bagged items - personally, I'd crack the dash open and rip out the voicebox if my car spoke to me. I would, however, prefer voice for serious hazards, or for some hands free operations, like device pairing. "Leaking oil/belt broken/wheel flat - pull over now" would probably save a lot of people a lot of money.

I suppose my point is the idea of "this plane is going to crash" demands a bit more clarity for users than "you left your lights on," which probably contributes to why tones are more common in the car.