That story mentions only one side of the coin.
The buyer from China wants to pay a price not more than X, and in China they say OK to get the order and do whatever (cost cutting at expense of quality) is needed to be able to sell at that X.
That "whatever" is thus a consequence of buyers demand.
Why does for ex a US company chose China instead of US as a source: because China does it cheaper including shipping and whatever trade costs.
A willingness to pay more means in China they don't have to cut costs, and quality is accordingly.
For ex lately, sport shoes. My size is EU 47
Brand "Reebok", is well-known, due to advertising, tagged as Made in Vietnam, as EU 47, no material mentioned, but I judge it as leather.
Brand "Polo", never heard of, tagged as Made in China, as EU 45, as 85% cow leather 15% fabric..
Guess what: the Reebok 47 ones were too small, and the Polo 45 suited.
That's how Reebok/Made in Vietnam had cut cost: by falsely labeling 45 as bigger 47.
The outer sole lengths were the same, so some1 just comparing on sight is fooled, but the upper of the Reebok was clearly shorter. A bit less leather/material.
The difference of the curves of the seat clamp parts is too big to be explained as tolerance / quality control. It's more likely that some stock leftovers of different/newer/older models were mixed in order to get rid of a remaining old stock.