Since you posted that you own a Toyota- does yours have the proximity sensor and push-button start? If so, is it possible to kill the motor without leaving the vehicle?
Yes it is. When you are stopped you just press the button. However for emergency stop you have to hold the odd button for three seconds. Individuals who have tried this say that the 3 second hold does not work. However in a panic 3 sec sounds like a long time. Under controlled conditions I have confirmed the three second hold does work
The next issue is the neutral shift. I can not find out if there is a mechanical connection between the shift leaver and the transmission. I suspect there is not, especially in the hybrids that have a continuously variable transmission. The shifting on pretty much all Toyotas since 2002 has been elecro solenoid.
The transmission has its own control module, which is typical of most vehicles now. There is tremendous interaction between the ECM module and the transmission module.
I found one solitary report of a Toyota owner with unwanted acceleration that claimed the car did not shift into neutral. However the situation self corrected and then the vehicle was fine.
There seem to be quite a few reports of this where there is acceleration and the problem self corrects before a tragedy. One thing all these reports have in common is that there are no OBD fault codes left of the incidents, and so dealers claim the vehicles are fine.
So that means either driver error, a sensor or sensors sending wrong but credible signals that the ECM does not recognize as error signals. The third possibility is that under the wrong set of unknown circumstances the software can lock up.
So Toyota may genuinely not know what is at the bottom of all this, and may not be able to find out without dumb luck if their accelerator fix does not work. Personally I doubt it will. For one thing there are credible reports of this involving quite a few Prius vehicles that are not on the recall list and do not contain that part.
I think the auto has now got so complex and dependent on microprocessors and software for vital functions, a black box needs to be mandated so there is a record of everything that took place. If we had this I doubt there would be any speculation, doubt and and anxiety about this problem at this stage.