Speaking only for myself... The process of calling a toll free number for a SF cab sucks. Often get a busy signal. Most of the time they are slow to respond.

Speaking only for myself... The process of calling a toll free number for a SF cab sucks. Often get a busy signal. Most of the time they are slow to respond. Some times they never show up at all. Basically, I can't count on them to be timely. Uber (and formerly Sidecar) just shows up in a few minutes and takes me where I wanna go.