I will fully cop to the fact that my previous bitching about taxis concerned a classic San Francisco yuppie firstworldproblem but here are some more stories about how taxis in many cities serve people of all stripes exceptionally poorly.
Relatedly, I took an UberX with a friend the other night and the experience was awesome. I might have liked the option of tipping the the driver (via the app, after you get out of the car), but UberX doesn't allow that. On the other hand, maybe tipping would establish a social norm for companies like Uber to underpay their drivers with the expectation of tips? I really like traveling abroad in countries that don't have a tipping culture; it seems more rational and arguably in the long run leaves labor in a better position since their compensation is assured by contractual terms rather than manners. So maybe it's great that Uber doesn't have tipping, only reviews.