Ubers attempt may or may not be a good attempt at solving the problem of maximizing market efficiency, however it operates under the assumption that we want to optimize for market efficiency. The current system treats cabs like a utility and ensures fair access for everyone, a property that Ubers algorithm does not account for. It maximizes availability and access for the wealthier among us, a property that's at least in germany not as important as in the US. Bad market fit, as I said. MyTaxi operates whithin the framework of the current system and retains its properties while adding value and efficiency. It's obviously not as efficient from a market perspective, but that's a feature.
Now a system that combines the desired properties of the old system with better efficiency is certainly thinkable and desirable, but Uber is not that system, at least not in it's current incarnation.