If this is true, this is a big deal. However study is inherently flawed because it uses only two cities for it's data. There are a number of factors that could have called this result to be observed, for example increase in SF's DUI due to more rigorous police patrols. I also did not see any seasonal controls. DUI rates might be different depending on the time of year.

Here is what would provide for a way stronger claim:

1. Aggregate DUI levels change since UBER started operating across all cities with no UBER service.

2. Aggregate same data for cities with UBER.

If UBER causes decline in DUI rates hypothesis is true, we can expect two trends:

1. On average cities with UBER will observe relative number of DUI's going down when compared to cities without UBER.

2. Amount of UBER rides given will be positively correlated with decrease of DUI rates.

Personally I think it would make sense that UBER decreased amount of DUIs and I would really like a data released that can prove it.