One of the things that's interesting here is what's the fundamental difference between using your phone to order a cab using your voice, and using your phone to order a cab with your fingers ( an app ).

Pricing mechanisms could be the same - pre-agreed price etc.

The real key difference is the realtime feedback of where the cab is in terms of coming to pick you up. ie the diminishing of the anxiety of that uncertain wait.

That's it - that's the only thing traditional cab firms couldn't provide - and now many of them now have their own apps - as apps aren't that hard.