> The US government values a statistical life at anywhere from $7 to $12M. Is there any evidence that this woman's lifetime earnings would've exceeded that?

Thats not what that means. "... when conducting a benefit-cost analysis of new environmental policies, the Agency uses estimates of how much people are willing to pay for small reductions in their risks of dying from adverse health conditions that may be caused by environmental pollution. [...] these estimates of willingness to pay for small reductions in mortality risks are often referred to as the "value of a statistical life.”[0]

> Is there any evidence it was Uber's policies or actions that caused this?

The arbitrator/judge believed there was enough that the company was legally responsible for the conduct and issued a fine to the company for that failure of responsibility to be paid to the parents -- not because he decided that was how much she was worth

[0] https://www.epa.gov/environmental-economics/mortality-risk-v...

That's about the closest value you'll find to what human life is economically valued at. Do you have an alternate measure that is grounded in anything?