From my experience in many places drivers actually use multiple apps at the same time. This means that there's less and less of a distinction between the safety, ratings etc. of each individual app.
Ratings is an easy to use and game feature (fun fact often harmful to drivers of color) that costs almost nothing to build. The feeling of safety was flatter Uber had a bunch of rapes that forced them to pretend that they cared, spend is very small on it.