I don't know if we can say emigrating Cambodians were in a worse position than impoverished blacks . Immigrants self select for being willing to leave everything they know for the hope of a better life; they have also competently navigated a difficult process. This selection bias is accentuated in war, when the logistics of escape become trickier. Communities then cohere and reinforce each other on the other side.

Contrast that with American blacks. Captured by coastal kings who sold them to Europeans who transported them here against their wills. Any who stood up or out got eliminated. Loose to non-existent intergenerational information and wealth transfer. Et cetera