China gets it’s copper from the same place we do in the US. Chile. The largest copper mines in the world are in South America and 59% of the copper used in the US is from Chile.
I used to be an engineer at Cooper industries (Belden wire and Champion Industrial Spark Plugs). Left after Federal Mogul bought us.
So the quality of the core materials used in the US and China are the same. Not the case in finished goods, a few good mfrs in PRC though.