What you say is true for the American market. Australia was allowed to get purebred cattle directly from Japan, the Japanese cattle breeds they have are pure to the genetic strains of the cattle in Japan....
I think what you are saying is that the standards for this type of thing are higher there and I believe that's true.....let's all hope so.
American Wagyu is definitely no more than 50% Japanese cattle genetics, but, this does not mean the beef is not good, in fact, much of the American Wagyu (the more correct terms) is quite good, and it grades out decently.