As Ben Thompson of Stratechery explains, Uber is a two-sided market- it has sufficient liquidity of both riders & drivers. Any new app would have to sign up tens of thousands of drivers to be even remotely competitive, and that would cost tens of millions of dollars in promos, marketing, etc. The first time someone tries UberClone and the driver is 30 minutes away, they'll close the app and never use it again. No VC is interested in financing all that for a very low margin business. Uber and Lyft have all the drivers and have all the riders- being unprofitable is actually a moat