Hailing or waiting for a taxi was a horrible experience in most cities. Leveraging the smartphone platform's ability to track location in real time, along with its ability to be connected and handle payments created a better service. This did compete with existing Taxi monopolies (which had enormous costs associated with rent seeking in many jurisdictions, not just labour costs), but it also competed heavily with non-consumption, car ownership, and car rentals for those on trips. The pattern of social life has changed in many cities where the inconvenience, lack of reliability, and cost of using a taxi had previously constrained peoples' options, and forced reliance on owning a car, driving when they shouldn't, or staying closer to their neighbourhoods or going home early.

It's true that most of what gets called Uber for X is just enabling casual labor, without significantly expanding the market, and that's why so few of them achieve anything close to an Uber-level of success.