“Why won’t Toyota release the black box info and the code to read it. That would settle the argument.”
Not necessarily. The black box records what the vehicle does, not what the driver does. If the accelerator pedal electronically controls the acceleration, instead of the old fashioned mechanical linkage, it would show the same results if either pedal was pushed to the floor, or a failure of the electronics told the computer the pedal was to the floor.
The computer data from all the cars systems is carried on a common data bus. A short circuit or failure of any component on the data bus could affect other systems.
The new “fly by wire” system on today's cars are an accident ready to happen in that when you step on the gas to increase speed the throttle opens by electric signal and stays open until something electrical happens. This system requires regular inspection and provided with lubrication. The electrical gizmo's at the end of you foot pedal is trying to act like the old fashioned mechanical linkage which was pretty much fool proof.