Haiti has been run by crooked thugs in a descending pyramid of power and control. All money was stolen and the population kept in poverty, and with no money they were unable to create a middle class = no industrial revolution from within. The ones in power built clothing factories and a few other. Overseers were cruel = wages and right low, the poor could not elevate up and out.
The DR lacked these crooks and was able to elevate its people.