Maybe I'm a cave person but to me just waving to hail a cab or just entering the first car in line at a taxi stand seems much more convenient than having to fiddle around with a mobile app and wait until it arrives.
Now, admittedly, the app I use most often is stunningly ugly and has almost zero features, but it -does- have the feature of 'reliably producing a taxi when I type my name and location into it' and so long as that part works I don't really care much about anything else.
(in several areas of .us I've found that the taxi experience is "call them, one might turn up at some point" so I can see uber's tracking of the car as it approaches to be a welcome security blankie for people who've been traumatised by the local taxis)