It’s not hyperbole to say that Uber is in battles in nearly all of its most important global markets. Whether you rank countries by population or GDP (PPP) you end up with a similar list, and you see that Uber’s fighting for its life in many of the top markets.
The largest three countries, both by population and GDP (as of 2013) are the US, China, and India, and Uber faces serious obstacles in each.
While Uber is well established in the US, it continues to face serious headwinds, including recent bans in Portland and Nevada, proposals for tougher regulations in a handful other markets (including New York), and lawsuits in California, Nevada, Illinois, and Massachusetts.