Traditional American culture is rife with shame. The concept of “manly men” is based on shame. The concept that women are responsible if they attract unwanted male attention is based on shame. The concept that anyone can succeed so if you don’t it’s because you didn’t try hard enough is based on shame.

I could go on?

Most of these aren't really "traditional", they're constructs of the post-WW2 era, where the government & mass media/advertising very consciously tried to institute strong "national unity" norms.

I suspect that the "traditional American" culture GP is talking about is frontier/immigrant culture from c. 1840-1929. There's a good case for that really being a "shameless" culture - you do your thing, I do mine, we'll grab up all the land and all the gold and all the prime industries and not feel bad at all for the natives we're genociding.

I mean sorry but the Japanese have a pretty strong shaming culture according to most of the world, that the things you think they should be ashamed of are not those they are shamed by does not prove any different.