Yes, I have also been thinking how a similar reward system would work without tipping. Just use a bonus system based on customer feedback. And the flow could be very similar to how it is with tipping.

It's not worse than tipping, but we've already normalized the obnoxious idea that every transaction needs to earn five stars. You know the places. The ones where they warn you "You're going to get a survey, if there is any reason why you don't feel like you can give us a 5 please tell me" (unsaid: Please sir -- they flog us for 4 star ratings). I can't imagine anyone I know not rating an Uber 5 stars, unless they were say, called a slur or the driver caused an accident.

So, I'm not sure how to best construct a system not open to "guilt gaming" in this way, but I would like to see one.