It was a well lit section of road (the dashcam video Uber released makes it look much darker than it really is, there is other video out there of the same section of road, you can find it on youtube) and it was a natural crossing point but a very poorly designed road/walk way. Almost any human driver who was paying attention would have spotted her from a big distance and avoided hitting her.

Video of the section in question: https://www.youtube.com/watch?v=1XOVxSCG8u0