The answer has three components:
1.Your data is inaccurate
2.Quality has become a hygienic factor for the most part
3.You are assuming quality is the #1 factor when buying a car
German build quality is far worse than Japanese – or is it?
According to their 2016 U.S. Initial Quality Study (IQS) , the top two spots for quality correspond to a Korean and a German manufacturer. Kia and Porsche. The first Japanese manufacturer on the list is Toyota, with BMW in #5.
If you look at the entire list, one can only conclude German quality is pretty good, and about the same, if not better, than that of Japanese manufacturers.
My experience is consistent, my VW CC has about 110,000 miles and runs like new. Maybe that’s why in 2016 Volkswagen passed Toyota as the World’s largest top car manufacturer.
Even though the perception might be that Japanese cars are better built, the facts do not support that claim. If anything, Koreans are the best built cars nowadays, with two of the four spots. Maybe a better conclusion is that the nationality of the brand is not a good indicator of quality.