Before Uber was available in Orange County, circa 2010-2011, I used an iPhone app to call a yellow cab to pick me up without having speaking to a dispatcher. I was able to give feedback about the driver too. Uber-style apps to hail cabs did exist, maybe they just weren't rolled out to all markets.
Before the launch of UberX, the Uber app positioned itself as a convenient way to call a black car/limo and, for drivers, to get some extra business between their "regular" calls. It was a semi-luxury though it only cost a bit more than a yellow cab (I only ever used Uber pre-UberX to get to/from the airport).
Really, other than surge pricing, I don't think Uber innovated very much on the tech side. Their success in disrupting cabs was rather down to flooding the market with supply, oftentimes in ways that flouted the law.