I have recently determined a new analogy to "rent a car for a ride" or "Its just like a taxi but without having to face those icky ethnic people (I mean seriously hipsters, whats so bad about meeting people unlike yourself? Try it, I like it...)"
Its like the difference between having mom do stuff vs renting a nanny. And all the social class and economic class based biases and fallout.
I think people use these services because they're efficient and cheap. Not sure where you live but the majority of Uber drivers here in DC are ethnic people.