Everything is affected by supply and demand. They sold high volumes in US. That’s why the price is lowered. MX green version sold in the US is around the same price as their QFR with common switches for the same reason (mx green volume is tiny).
Don’t forget US also consume the most resources in the world (per capita) and produce the most wastes and pollution.
As much as we enjoy the low price of imported goods, I am not particularly proud of for the above reasons and am trying my best to go green whenever possible.