Why are Japanese people so quick to call food prepared by a white person as unauthentic?

I don't know much about Japan, but my wife is from India. I have noticed that most Indians are often very particular about Indian food. It wouldn't surprise me if that wasn't a fairly common thing for people of many ethnic groups to be very skeptical when someone who isn't from their group professes some knowledge of their style of cooking, and many other cultural things. You would have to do an exceptionally good job of it to be considered okay. I can understand why they might feel that way.