In San Francisco (due to what I hope was a uniquely bad system), calling and scheduling a cab was theoretically possible, but in practice unreliable and frustra

In San Francisco (due to what I hope was a uniquely bad system), calling and scheduling a cab was theoretically possible, but in practice unreliable and frustrating. Dispatchers had no way to locate an available cab in any reasonable time, and even cabs that agreed to pick up a call would often not arrive because (I was told) they would pick up hailed rides on the way to a pick-up. I missed many appointments when dispatchers took thirty minutes to tell me that there were no cabs available, or when an agreed cab never turned up. I don't think this problem is true of every city, but Uber was clearly an improvement on the existing taxi system in San Francisco. (In fact for many years the main topic of conversation between me and cab-drivers was speculating on how the SF cab system could be improved, and we'd often end up inventing something like Uber, or now Curb. I'm pretty sure SF would not have got to a reasonable system without pressure from Uber and Lyft -- it took them many years to get to what we have now.)