Yea, that's tricky. The simple way would be to treat all people equally, e.g. charge $1/kg for every passenger. But if weight correlates with race, even though

Yea, that's tricky. The simple way would be to treat all people equally, e.g. charge $1/kg for every passenger. But if weight correlates with race, even though each individual is treated equally, different races aren't being treated equally. Personally I'd rather discard the idea of race, what good has making those distinctions ever done?