Presumably the biggest factors will be education, and a lack of superstition and as you say, religion. I imagine it's not just a factor for the person donating,

Presumably the biggest factors will be education, and a lack of superstition and as you say, religion. I imagine it's not just a factor for the person donating, but also a consideration they have for their immediate families. I would guess that another community which donates a lot, are lonely people without those connections, who feel like this could be a last sort of service to the community.