In my experience, whenever Uber is surging enough to make cabs cheaper (2.5x in my city), there are no cabs to be found. That or the cabs try to scam you by asking for extra cash off meter (happened to me on New Year's Eve).
because taxi drivers cannot, at least where i live, by law, change their fare. uber/lyft told me (and i agreed by using their service) they would change the fare based on demand.
