[pessimizer]

I'm not sure why you think that other countries are in general by nature more homogenous than the US. Most of the countries that outrank us have engaged in massive internal orgies of slaughter over their differences.

>these metrics are skewed greatly by historical and regional concerns that are outside the control of the federal government

These metrics aren't "skewed" by, they are determined by. That your concerns (if I translate "ethnic heterogeneity" as "racism") are the reason for the bad numbers is clear. The reason that they should be excluded is unclear.

Racism and easy access to guns are written into our constitution.