I live in Asia. Been here for 20 years. If you don’t run your own QC (Apple obviously does) then many of the locals in China feel as if they’ve achieved something spectacular if they can get away with dropping quality midway, to pocket more money. It’s an endemic problem in Asia, and many, many foreign companies learned the hard way.
US manufacturers once took great pride in “a job well done.” Japanese manufacturers are about perfection. Germans will over-engineer a product to amazing specs. But Chinese will wheel and deal in a lightning fashion, then pull the rug out from under quality and feel absolutely giddy if they can get away with giving less than was ordered. Proud, in fact.
Of course, there are companies who have learned long term gains are better than short term cheats. Juggernauts like Apple will give their business to the first group, and dump the rest like a bad habit.
It’s not racist to call this out. China is not a race. It is a cultural issue they have been changing (but it still exists). Korea was once this way, but it has become a world leader in tech, and they are darned proud of it.