I think they figured they can extract that via market terms, such as bonuses for those driving X+ hours weekly (where X is a fairly large number) or never-ending chain of orders in UberPool.
Sure if they can keep the drivers at near 100% capacity then this would work, but this is hard to do.
A small competitor can piggyback off their network at low cost and be hard to dislodge. It is difficult to extract monopoly profits with an open network.
