So who is the real dummy?

The story going round the internet has the inventors of a self driving car doing a demo in DC.  They get Eleanor Holmes Norton, the District's sole non-voting Congress person, to take a ride.  She gets in the car. "Ohh, what does this do?" she says.  This is a large red button marked "Emergency Stop".  She pushes it.  Emergency Stop worked, the car didn't move, and in fact they were unable to get it to move again  End of demo.
   Most internet pieces poured scorn on Norton for being so dumb.  Speaking as an engineer, that button is broke.  Emergency Stop in a self driving car is supposed to let the passengers stop the car if they see the auto driver doing something scary.  It isn't supposed to cripple the car for good, leaving it stopped in the middle of the street.  I'd call the designers of the car dumb.