So even if globalization made America richer on average, it also destroyed the fair redistribution mechanism.

I don't have as much lived experience of someone in Vietnam as I do someone in my community. Nor do I understand the language or the culture. There's more overhead in making it happen and there will likely be a lot of things I'll never take into account or understand. On the other hand, I know what it's like living in a HCOL state where many jobs don't pay enough for a family to survive and have struggled in my own past. Could my money have more purchasing power elsewhere? Sure. And they're still people in my community struggling and I have the power to help them and a greater understanding of what they're facing. Community seems to get discounted a lot in the discussion around effective altruism and I think that's unfortunate.

They also ignore that even if other rural areas are technically speaking more rich than the rest of the world, still struggle with an extreme shortage of opportunity, upward mobility, and sense of purpose.

I speak from experience, having been raised in one such area. Had I not moved to a tech hub in search of greener pastures (which is not something everybody is capable of), my life would look so different now as to be unrecognizable. Instead of earning the upper end of the salary band for my line of work with numerous upward trajectories to pursue and a solid bit of retirement stuck away, I'd be working a job earning maybe ~20% as much that doesn't keep track with inflation with zero mobility and a fraction of much retirement funds, and that's one of the best possible outcomes in that region and inaccessible to most.

I've not aligned with the area I hail from politically for a long time now, but clearly it needs help.