While there may not be any perfectly equitable system, it is clear that those systems that run largely on out-of-pocket payments (as in most developing countries) or private insurance-based systems like the US (where insurance providers often participate in adverse selection to decrease their risk) largely are not equitable.  While health systems that provide universal coverage are generally more equitable, there are still other considerations, such as how funds are raised, the distribution of healthcare providers across the country, and so on. The reason for the mixed success of many donor-funded rural insurance schemes is complicated.