Alibaba has a crowd sourcing program that pays people a few cents to identify images for them. Like a hybrid of Google Crowsource and Google Rewards.
China has over a billion souls with access to smartphones. Take just 1% of that and pay them some cheap beer money, and within a few hours you have hundreds of millions of images and datasets to feed to an AI.
That's what makes China's AI research so powerful. Math is certainly a crucial component, but if you provided a similarly massive data set to US scientists they could get similar results within the same period of time.