France required compensation money in exchange for recognition of Haiti (which was Haiti's only choice at the time, nobody else wanted to recognise them). Because of course Haiti didn't have the money nor any realistic prospects of coming up with the money soon (not only was their infrastructure decimated by the slave revolts and civil war and revolution and various campaigns, their cash crops were only viable with slave labour, so unviable in the free Haiti), French banks provided loans at exorbitant rates to pay France. Those loans were the ones that Haiti was still paying, to French banks, not France the country. Banks have zero interest of forgiving loans, regardless of ethics, so it's not at all surprising they never did.