A number if people have remarked on the dramatic differences, especially in death tolls, between Chile, which actually experienced a far larger earthquake, and Haiti. Chile had fewer casualties and fewer buildings collapsing -- though it is apparently still experiencing aftershocks. But not many got to the most important reasons. Some cited building codes in Chile, but Haiti could have had the strictest building codes in the universe and they would have been ignored because most people are too poor to build to them. The biggest key is wealth, and Chile is wealthier not only because it has a history of being relatively civilized, whereas Haiti's history is unspeakably tragic, but it had something of a free-market revolution in the 1980s that laid the groundwork for a democratic revolution.
Don Boudreaux at George Mason U also expounded on the differences in property rights. Chile's are relatively secure, while in Haiti property rights are less secure than in almost every country. Who has the incentive to build to high standards when your property can be taken away on a whim?