That goes for anything made under contract for other companies. The manufacturers will make what ever a company wants to the customers specifications. An it also doesn't matter where the manufacturing plants are located. Junk specs and/or trying to get things as cheap as possible results in poor quality items being manufactured.Just because a company touts Japanese glass, it doesn't mean you're getting Vortex Razor or Nightforce quality. Japan can make mediocre glass too
I definitely tell a difference between the exact same scopes (Arken SH-4) with one having Chinese glass and the other having Japanese glass. The Swampfox Patriot 6-24 scope and my lower end Primary Arms scopes all have Chinese glass too. And the Arken SH-4J is definitely better. The Arken scopes with Japanese glass still aren't as good as my old Bushnell Elite 6-24 scope.