I'm Not "they" ... they are working at a factory on the other side of the Pacific Ocean from Here, and don't have time to read this Forum.
High Volume Production the parts Go Into Jigs & Fixtures to speed the work, But probably are not taken once finished ,
to a Dial Indicator laden Alignment table .. and twealed to the nearest mm,
like your multi thousand dollar Hand made American Steel Pro Race Bike frame, May..
...