The original idea behind "ride-sharing" is just as that phrase sounds like: it was about carpooling. We are going to the same general location, so to help get cars off the road, I can help you out with gas costs, and we both come out ahead. The app facilitates finding drivers and riders in the same area, going in the same direction.
By that measure, Uber pays drivers (and charges riders) too much already. The fees should be just enough to cover fuel costs. If drivers are doing this as a job, then it's not really getting cars off the road. By driving to places that they would not normally be going anyway, traffic/fuel consumption is not decreased.
If drivers want to make a living carting people around, they should go hook up with a limo or taxi company. The stories of people buying new cars just to become Uber drivers is insane. It's exactly opposite of the (original) intention of the company. They would be well-served to get back to their roots, and avoid all the questions about contractors/employees/unions altogether.