Note this isn't merely a Chinese thing. A variation of this is in fact the default way new units get build and sold in the Netherlands, for example.

Personal anecdote. I had a mortgage for 2 full years before being able to move in to my apartment because I bought it before a single stone was laid. The way this works here is that the money is held into an escrow account for most of time, with the construction company only receiving payments in installments (e.g. 'roof finished'). Lastly, the final 5% of the purchase amount is held back until 3 months after the unit is finished, which can be extended if large defects are found. Bankruptcy risk was covered with an insurance, which was a condition to the mortgage.