Very thought provoking post!

Numbers can be cold but problems faced by a larger group can invoke equal reactions as the sad story of one. Two key things matter here - one how descriptive or stimulating is the text used to decribe both and second, is the audience for both different? A person that has an imaginitive head will see the suffering in numbers. A statement like "1 in 10 children in the US are malnourished" will draw his/her attention to the fact that kids are not being fed well and he/she will think of a poor weak kid in torn clothes. There will be compassion. A statement used to decribe the same text as above that says "1 in 10 kids arent able to find enough food and live a life of indignity and extreme poverty" will generate more compassion and emotion.

Clearly, based on your example, statistically it seems to be the case that larger group of people that have faced suffering get let compassionate responses. May be the mind plays a trick as people think about an absolute total sum required to help those in need (thus for a larger group, the per capita amount is lower). Second, may be our bias is affecting the donations. Pictures of kids from africa or middle east may draw lesser compassions as people from these countries have be duhumanised over the course of history to justify killing them as a side effect of war (however the studies you have cited do seem to take care of this bias). And war makes sense to the govt. The rhetoric helps sell guns that in turn funds a political campaign and gets one into power by forming the government. It also means more money for the shareholders of defense tech companies.

The post was a great read. Thank you for writing such good content.