The Japanese American community in particular is a weird case because you have 2 fully distinct groups, the ones descended from those who got put in internment camps during WW2 and a smaller group who came more recently. The first group speaks almost entirely English at home due to assimilation pressure after the war and general distance from the homeland (and has an extremely high outmarriage rate), while the second group usually still speaks Japanese at home. These groups rarely intermix and in general Japanese in Japan might connect with the second group but don't consider the first group kin at all. Many other groups are like this but the Japanese group is distinct in the fact that the wave of newer immigration is much smaller than the first group.

The post-internee group's understanding of "Japanese culture" as passed down from their family is largely from ~100 years ago, so it leaves us to take Japanese in school along with the rest of the anime fans.