Modern China is a vastly better place to live than China of 60+ years ago. Many countries are nicer places to live, but 1+ Billion people are simply better off making the “exploitation” narrative ridiculous.
How about before it was partitioned into colonies of various European powers? Population of China 60 years ago was half what it is now (700 Million).
Anyway, the answer is both. They were being exploited 60+ years ago, and they're still being exploited now, regardless of if they can take the train away from the factory that they work at to visit their relatives over the holidays.
Porque no los dos? Given the number of billionaires in China, it can both be true that workers are exploited, meaning they could earning more for less hours, and that the living conditions are better on average and possibly medianely than the local minima of 1966.