If a driver's average rating falls below 4.6 Uber typically removes them from the platform. A rating of less than 5 stars is treated similarly to if a customer reported a driver for poor service.
They’re a tech company;a decent rating algorithm should be one of the most likely things for them to excel in, or they’d just lose to any company that does because all the good drivers they’re dropping are immediately signing up to work for a competing service.
tl;dr It is in ride-services’ best to retain good drivers, no?
Until that meaningfully changes I don’t think they care about anything but earnings.
Interestingly, that attitude is what allowed them to come in and replace yellow cabs as the de facto driver for hire option.