It's not that hard to set up a business like Uber if you only start with one city. You don't need a global business. Taxi businesses also always worked per city. As soon as it'd be lucrative, there will be some competition in the city where it's worth most.

Sure, you can't just copy uber's app. But building a simple app with basic functionality isn't that expensive. And people will mainly decide by price.

Their only chance to ever make back the losses is the self driving business. If it works out they could be very profitable. If it doesn't, I don't believe that they'll ever make back the investments.

Amazon is actually a good example. They also haven't really made back the investments. They're still not very profitable. Maybe they never will be, who knows. As long as enough investors believe in them they can comfortably afford this style.