In traveling from Cap Haitien to Labadie, a beautiful resort area of beaches for Carnival Cruise Lines, we wound up mountains with gorgeous views of the ocean around each bend. The road surface, though, was like driving in a creek bed. Only four wheel drive vehicles really serve travelers there. It doesn't take many months to loosen up a brand new vehicle. This doesn't keep people off the roads, but it certainly becomes more complicated.
Private vehicles are for the few.
Most go on foot. For longer distances, trucks and pick-up trucks become the taxis and buses. For people living outside of towns a walk of one or two hours to go to any market is very common. A massive road maintenance and building program is a major need. Another reality in Haiti is deforestation.