I actually think that it will be the size of the cut that they take that will be a factor in determining if they are employer or not. As you say if they charged

I actually think that it will be the size of the cut that they take that will be a factor in determining if they are employer or not. As you say if they charged a flat daily fee (as hackney cabs (licensed taxi service in the uk) do) then they would not have this issue. But as they are taking a cut of every fare, or another way is that they pay the driver a cut of every fare, it seems much closer to employer/employee relationship, at least in UK law.