I would bet that collectively the time wasted due to mishaps exceeds time saved by this feature. For me personally, I don’t think I will ever make the time up in my lifetime - I have accidentally killed a battery once because the car was in ACC mode and I didn’t realize it, and another time I drove away without the key because I was dropping the owner of the car off at the airport.
These problems are not as bad with an electric car like a Tesla. I have left AC on but the battery was fine. I have been dropped off while the driver had no key, and it posed a slight issue once they stopped the car and got off the seat. Obviously, no CO poisoning.
I always thought all cars had alarms for these cases. Similar to when your child throws the key out of the window while driving. Shouldn't happen but has happened (there were some news stories on that last year) and there's no reason the car shouldn't give an alarm.
