White Flight in America often coincided with decreasing real estate value.  Therefore, the direct motivation was never racism but more the fact that families wanted to preserve their assets (the home is considered an investment).

I think the principle difference is that someone can stand to benefit by having a wave of wealthy immigrants who prop up a massive housing bubble.  As the old expression goes, 'money is king'.

I think in previous heterogenous societies, it's always fun and games and smiles between the large ethnic conglomerates until the economy or livelihood crashes.