Hundreds of trips on Uber, in Australia -- There is no tip culture here. Out of those hundreds, I've had two ask for positive ratings, absolutely none ask for a tip.

With drivers who have seemed friendly enough I've tried to politely and diplomatically inquire about how fair they feel the system is. Several ex-taxi drivers have told me it is better than driving for an official taxi company in every way, including pay. (Note that taxi drivers are never tipped either.)

I have been surprised by the number of people who have been driving for Uber as a bit of cash on the side, and not as a primary income -- all of them have told me it's "worth it" except for learning a lesson early on not to drive late at night and pick up drunks, as the chances of having to clean up after an extremely messy fare is too high.