Chinese companies are rushing to deploy low-flying vehicles and drones for various uses as the country finds innovative ways to drive its economy. Flying taxis, once a sci-fi dream, are being tested in southern China, where pilotless, oval-shaped crafts hover like mini helicopters. In Shenzhen, which neighbors Hong Kong, food-delivery drones already are part of daily life and a novelty attraction for tourists. The industry is growing with support from the government, but strict airspace controls, battery limitations and other obstacles are hindering the rise of the low-altitude economy. Analysts say the industry is still in its early stages and more obvious successes in commercialization may take years.