The car detected an obstacle, but had emergency breaking disabled by Uber, so it didn't stop. According to the article, the system didn't alert the driver of an obstacle despite detecting it.

To me, that's an insane failure mode.

Note the emergency breaking system isn't part of the Uber self driving system, rather it came from the car manufacturer. Uber simply disabled all the settings, including all the safety features.

[1] https://www.npr.org/sections/thetwo-way/2018/05/24/614200117...

Right. They disabled Volvo’s system and their own emergency braking didn’t work (apparently created too many false positives). It was criminal negligence to put the car on the road in that situation.

That makes them less responsible (as opposed to liable) how, precisely?

Their system detected an obstacle and did nothing as it slammed into a woman at 40mph.