Last I was in Beijing, taxis are plentiful, no need to use an app to flag them down. Also, taxis in Beijing are a lot more regulated than any of the US cities. Once, my cab driver got quite a bit lost and my fare ended up almost double what it should have. Friend called cab company and they quickly sent the cab driver to my dorm to apologize & hand me a full refund. My friend explained that the taxi company could be in serious trouble if we report it to the authority.