https://techcrunch.com/2018/05/24/uber-in-fatal-crash-detected-pedestrian-but-had-emergency-braking-disabled/

The initial report by the National Transportation Safety Board on the fatal self-driving Uber crash in March confirms that the car detected the pedestrian as early as 6 seconds before the crash, but did not slow or stop because its emergency braking systems were deliberately disabled.

Uber told the NTSB that “emergency braking maneuvers are not enabled while the vehicle is under computer control, to reduce the potential for erratic vehicle behavior,” in other words, to ensure a smooth ride. “The vehicle operator is relied on to intervene and take action. The system is not designed to alert the operator.” It’s not clear why the emergency braking capability even exists if it is disabled while the car is in operation. The Volvo model’s built-in safety systems — collision avoidance and emergency braking, among other things — are also disabled while in autonomous mode.