Another idea would be to have user ratings and feedback. I'm not sure if these services already do something like this, as I've never used them, but it could give hosts and drivers a means of rating their users so that they have some additional criteria by which to judge whether they want to loan their resources to a particular customer. That won't really solve the problem of new black customers who would have no prior rating, though. Maybe a criminal background check for customers is in order if people are really worried about being robbed or assaulted or some other nonsense. Of course that could cost time and money and could destroy the convenience factor of such services. A real bummer of a problem. I wish people were better.