I'm kind of suspicious that according to the article the same factory is making 'bad' pens for China and 'good' pens for export. I'm no expert on process improvements, but it would generally seem that once the cost to create the good pens has been spent, it would be relatively cheap to apply them to both product lines. Which suggests either they intentionally use cheaper parts (cheaper ink?) on one line, or they have…
More generally I've had products manufactured in China for sale in Australia, and they certainly had more expensive parts than products assembled on the same line for sale into China. Never in a million years would the domestic units have passed certification for sale in Australia. So you just keep slotting in more expensive, higher-spec parts until the unit's safe and saleable.