The F3, F4 had Italdesign, but it was mostly cosmetic. But prior to the 1980's, I think it was all Japanese design. The Nikon rangefinders borrowed Contax styling, ok.
I credit Japanese rangefinders and SLRs as being of Japanese design, not Western.
Just look at the cameras being designed in the U.S. in the 1950's or the SLRs of Europe in the 1960s (Voigtländer, Contaflex) - the leaf shutter lenses, the EV linked shutter and aperture - nothing at all like Pentax, Topcon, Canon, or Nikon.
The market spoke 60 years ago; we have better cameras for it.