Haitian Zombi Hypothesis - Is Haiti a Drug Free State?

Haiti is a small country, but it has a population of 11 million. The authors in the lancet write that bakors actually enslave zombis on secret agricultural grounds is implausible given the high population density of haiti. Zombes have never been identified in captivity, but only on their return. So maybe some of those abductions cloaked in voodo were incidents of zombification.