I don’t think this is accurate, Chinese firms are increasingly moving up the quality chain. You might want to look at some of the reviews of Xiaomi’s recently launched car. Also, Tesla Shanghai is one of their best factories, much better quality scores than Fremont iirc.
Having a totally local, integrated supply chain pays dividends in a lot of ways, as does leading in production volume. Tim Cook also gave that interview where he was just talking about the incredibly deep bench of industrial talent that you just can’t find outside China at this point - that labor cost wasn’t why they produced there.
From what I've heard, the quality is pretty good. The problem is when something breaks, you can be waiting for (sometimes very expensive) parts for months while not being able to use your car.
it took Japan about 25 years of very directed industrial strategy to take the "made in Japan" label from indicating junk to the average American, to indicating a premium/reliable product. China might get there in even less than 25 years but you'll probably still find people holding onto old "chinesium" beliefs long after they should
The issue is not actual quality, it’s perceived quality. Chinese companies will fight decades of history and negative perception to reach top of the market consumers, a segment obsessed with perception.