One of the best parts about Uber is that you just request a ride and it shows up. The whole process takes seconds to complete, and a driver is there within a few minutes.

If I had to peruse a list of drivers close to me, find a balance between price, rating, and proximity... then request a ride from that driver.... and then have to repeat that process when the driver declines the ride or has already taken another fare.. I think I would call a cab.

The entire key to the success of Uber is the ease with which you can get a ride fast. Your idea of a craiglist-ebay hybrid for selecting a ride wouldn't work.