Having worked for a thriving competitor of those brands, I can tell you that the app was not the major factor of success for the company. Our infra, at the time, was retarded, the code quality was mediocre, and we witnessed major downtimes, fun times. You have to come at the right time (for vc money), organize operations efficiently (recruit drivers + passengers) and make some lobbying to not be banned outright, while managing angriness from drivers, and unhappy clients. This is the hard part. The tech is basic !