If they use their momentary advantage to push out other legitimate options for transit, then there is a good argument for regulation protecting riders.

Maybe Uber shouldn't be making any decisions about users. Just present the rating to the driver pool and let drivers decide who they pick up and who they do not. It doesn't entirely solve the issue of "what is a justifiable reason for rating a rider (or driver) poorly?" but it makes it less catastrophic for users.

Given that taxi's were the only legitimate option for transport before this, were there regulations protecting riders from being banned?