Koopman has a talk here on his blog that has more details about how ETCS (Electronic Throttle Control System) is safety critical. "If a driver pumps brakes, loses vacuum power assist...WOT requires an average of 175 lbs of force on brake pedal"

And what was particularly negligent about Toyota's software practices that "more likely than not" caused issues with ETCS.

https://betterembsw.blogspot.com/2014/09/a-case-study-of-toy...