The study might matter to us and regulators, but the thing that matters to drivers is how much they as an individual make. They had that information already, and knowing the average income doesn't help them figure out how much money they're making.
That can be confusing for drivers for some months as they may not realize the increased maintenance cost for a little while. But eventually they'll figure it out.
The evidence I can observe is consistent with the hypothesis that Uber and Lyft are paying sufficiently to motivate drivers.