I would just like to point out, that the crimes aren't necessarily under-reported (i.e. 706 reported), rather, there was not enough evidence to convict.
I would still argue that there is a high amount of under-reporting because people are embarrassed, just want to put it behind them, etc. However, I also feel a large number of the reported cases are skewed due to angry ex-girlfriends, intoxication, etc.
Specifically, in this case if he was not convicted it's not the responsibility of Uber to disclose that information (instead it's the driver). Uber (in the U.S.) cannot even disclose if someone was accused of rape (unless there was a felony conviction), conversely it is the drivers responsibility to share any convictions upfront (though a background check should still be done).
Overall, I believe this has more to do with Uber's business practices. The rape wouldn't have even been an issue if Uber was capable of helping the police or explaining some basic questions.
In other words, if Uber was able to say, "We did a background check, and he wasn't convicted" then there wouldn't have been an issue. However, Uber couldn't even be contacted, and was breaking transportation laws.