I actually completely agree with all your points. I didn't mean to say these are insurmountable barriers, just to provide some counterweight to the argument there are no barriers to entry. One particular weakness you and others called out is that the network is mainly split into separate cities. So a competitor doesn't need to compete with Uber globally, but could just target a single city.

Additionally once Uber reached monopoly status and started raising prices, it would become more attractive to new entrants to enter the market. So even if Uber managed to beat all their competitors they still would have a price ceiling. All in all I think Uber provides a valuable service and can probably turn itself into a (very) profitable business, but I'm not convinced it will ever be the undisputed leader of all things transport that its current valuation seems to imply.