> However, Uber requires an absolute minimum score of 3.8 for drivers to stay on the platform, and a 4.6 minimum for any area that has reasonable driver supply (eg: everywhere). This means every time you rate a driver a 4 it's effectively a statement that they should be fired.

No, it's a statement that the quality is what the customer would rate as a 4 on a 5 point scale. If Uber'a expectations of ratings are unreasonable based on the way it's customer base assigns ratings, then it is Uber, not customers, who should adjust.