I've linked them below, but just looking at the factory processes, the workers, and the methods used it seems the German process is just designed to build cars with tighter tolerances. The cars don't move down assembly lines with humans touching them (in the 911 factory). When a human is working on the car, the car isn't moving. Compared to the Corvette (much cheaper, but still "high end") you can see how quantity is prioritized, and how the car never really stops for any extended period of time, before moving down the line.
Again, this is a totally subjective opinion, but comparing my current car (VW) to a similarly priced Ford I test drove the other day (GT350) the difference in build quality is night and day.
This is a Porsche factory, building an expensive, high end 911 - https://www.youtube.com/watch?v=BbcKZ1lRDuA
Here is the Chevrolet Factory building a Corvette - https://www.youtube.com/watch?v=9ccOrwFs3No