> as nations get richer they become more environmentally conscious, cause they can afford to care about it.

Thus far, getting rich has been dirty business. This is what leads people to care more so than them being able to afford to care. Their richness is a side effect of their pollution, thus, caring is a side effect of richness but that's not the root cause. Pollution -> Money -> Caring. If you removed the money, people still care they just can't afford to do anything about it.

I'm not familiar with Pinker or this theory, just poking at it :)