I mentioned Canada and France. Could also list other countries like Austria and Netherlands that had similar issues. Hell, even Brazil, who had been improving economically and especially for its poorest people consistently since the 90s, and was taken over by a far right government that rose through social media, exactly the way Haidt describes.

My point is that what we are witnessing here is better explained by the sudden access to social media rather than socioeconomic deterioration. By the way, we agree that the working class in the US (and UK) have also experienced a relative decline in the past decades.