Earlier quoted context omitted.
I second that fear. Remember the Segway bug that caused the motors to spontaneously reverse? Imagine that on the highway at 60mph.
There's no fear of catastrophic failure at 60mph on the highway, if its motors are only capable of a top speed of 40mph. It's not a highway vehicle. Aerospace has used fly-by-wire computer-controlled unstable vehicles for years. I trust a well-designed computer more than I do an average motorist.
40mph can still kill.