I too expected more from HN and I think it's because HN is generally more civil than other webs forums. I think the credit of this civility goes to the HN moderators and the enforcement of the policies, not because HN types are special. I used to think technical minded folks are more analytical and thus have less tendency for bias and generalizations but I've concluded that ultimately tech people are still people and subject to the same filters as "normals".

I hope you not discouraged from pursuing your specialization in the US.