I'm not sure, but I think because the Emancipation was achieved by the intervention of foreign powers.
Information:
The Haitian Revolution has often been described as the largest and most successful slave rebellion in the Western Hemisphere. Slaves initiated the rebellion in 1791 and by 1803 they had succeeded in ending not just slavery but French control over the colony.
The political, ideological, and economic consequences of the Haitian Revolution were profound, including inspiring the German Coast Uprising, which was the most serious slave revolt in the United States; the Louisiana Purchase, in which the United States obtained much of the Western United States from France for a very
