Since nobody seems to have any idea how much these things actually pay after costs (see: this correction and the original study), it's plausible that people would expect this to pay more than it does.
Also, it's really difficult to define the one, right way of correcting for vehicle expenses. Some people would even work for free if it just gave them access to a high status car (live off savings while pretending to have "made it", as proven by the car). Others would be fine with any old beater, or a bike.
The difficult thing to calculate in the short term is wear and tear on the vehicle. Average Joe is potentially only counting fuel and not total costs per mile.
No, but I worked at a pizza place for several years. Everyone was vaguely aware of the fact that they were using up car value delivering pizzas, but only a couple of older full time "career" drivers seemed to actually calculate it out so they knew what they were getting.
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.