I linked last week to Matthew Yglesias's Slate piece "The Best and Simplest Way to Fight Global Poverty," which reports on a study that gave unconditional cash grants to poor young adults in Uganda and found that four years later, recipients of the grants had more business capital and higher earnings than those in a control group. I thought about the study again over the weekend as I listened to a Planet Money podcast about a charitable school-building project in Haiti that exemplifies how hard -- and potentially less effective -- it can be to give poor communities assets like schools rather…