It's a dangerous game. With the cost of ride essentially being an unknown, ranging from cheaper than a cab to many times the cost of a cab, I often wouldn't bother either. People prefer consistency in what they pay for an experience, and when it's inconsistent, I lose trust that the value will be consistent (ie. Uber for most people I believe is attractive if the experience is better or equal in cost to a cab, but terrible when the cost is significantly higher than the convenience/better experience.) At least with a cab I am (fairly) certain of the value.