Is there really big change in congestion? If not Uber, people would take a taxi or drive themselves - that's what I'd do. Both cases don't reduce congestion.

As for insurance, there are tons of people on the road with bad insurance, at least for Uber as I understand you have something to back it up.

As for assaults and other bad apples, that could have happened with taxi too. I don't believe any company of these proportions could have checks that could 100% prevent such cases. I'm not sure it's possible in even in principle...