@wozniacki most likely bases those opinions on second hand knowledge. It's hard to imagine why Uber isn't so in demand in many parts of Europe until you see the quality and price of the competition there.

Before hailing a ride I always check Uber and taxi apps, all of which give me a spot on estimation o price. Most times I have to choose between a Mercedes (C/E class, so large and comfortable) taxi and a Uber (lower class car), the Uber ended up being more expensive. In some countries Uber will still offer better price or price/quality ratio but this is far from a given.