I don't drive Uber, but on Lyft if a driver or passenger gives a 3-star or below rating it's considered such a poor ride that they won't be matched up again. Far from "average."
That genuinely surprises me. I really would have thought 3 stars means "it was fine". This issue would actually make me think twice about using Uber or Lyft. Is it OK not to rate a driver at all?
As of late 2018, if you don't rate your Lyft driver we automatically get a 5-star rating for that ride. That further emphasizes how crucial keeping a high rating to Lyft for the driver.
It genuinely surprises me that you expect more from a ride than getting there.
What makes you think that I expect more than that?