Obviously Uber in this case, but as mentioned in response to a separate article, AI's must be like pets or children and have a liable guardian.
Like my comment says, let's wait until we have facts before passing judgement.
But from this distance, things don't look good for the technology or the future of autonomous trials on public roads.
The evidence that due care was not taken will pretty much be the existence of the fatality.
There surely will be video, from the car itself and also perhaps third party security or traffic cameras. The level of carelessness we are going to have to see in order for a jury to blame the victim will be pretty high.
As for a fatality proving that due care was not taken, I agree. It doesn't tell you who failed to take due care though.