Is it? I prefer Uber/Lyft because it's convenient (both in arranging the ride and payment) and auditable (account records) and accountable (driver and rider ratings). Being cheaper is a benefit, sure, but I'd still use it nearly as much if it cost the same as a taxi, which I rarely (if ever) used in SF before Uber, because their service level is so bad that I preferred to drive myself or suffer the discomfort, dirtiness, and trip length of Muni.

Yup, I'm merely one data point, but my POV is hardly unique.