Have you ever tried pointing out the obliviousness to your German friend?

I'am an ethnic Chinese living in Japan and essentially blend in. I've also spoken with a lot of other expats, often white who complain a lot about (sometimes positive) discrimination and just once, rather offhandedly, I replied that now you know what it feels like to be a minority. The instant reaction is to become defensive, but after a while, the bulb lights up.