According to the official history Hassen's family has been running the ferry for generations. It has to have been at least one hundred years since one of his ancestors was taking King Aliphim hunting on Isle of the Forest before it became Isle of the Beast.
Only his family knows how to get through the rough waters of islands, and they have done this for more than two generations. They were important to society as they were the only way for the citizens of the Green Isles to contact each other and travel around the lands of the kingdom. There are no other boats.
"The family that runs the ferry has done so for generations, each father passing on to his son the secret of the tricky navigation. Many believe that the ferryman`s family line has an uncanny instinct for the sea around the isles. It is said that they sail " by the blood in their veins". One thing is certain: I would not venture to sail a ship in these waters, so whatever the secrets of the ferryman`s family - thank the stars for it!" -Guidebook to the Land of the Green Isles.
I'm surprised you missed that bit of information.
At least by original intent of the old games, he was intended to be a citizen of the green isles. You really can't go by sound of their accents to claim they are foreign, cause green islanders are diverse and every single character in KQ6 had a different accent, :p...
Even Ali, Hakim, Jollo, Guard Dogs, Beauty, her stepmother, and lamp peddler on the Isle of the Crown each had different accents but were supposed to be citizens of the islands :p...
Also the guidebook hinted that ship was maintained by its value to the kindgom.
All travel between the Islands is focused at the docks and, indeed at a single vessel, That vessel is simply called "the Ferry" and it is a pleasant enough little ship, well- maintained as befits its value to the kingdom. The ferryman is a jolly fellow, patient even with the youngest of his passengers. His young son helps manage the vessel and helps keep her shipshape.
.
A bit more on history of the ferry;
Beyond the village lie the docks, a place of bustle and excitement, Even the humblest citizen of the Isle of the Crown frequently enjoys visiting the other islands in the kingdom. In return, it is not uncommon to see all manner of strange creatures frequenting the village shops from the kingdom`s other islands.
All travel between the Islands is focused at the docks and, indeed at a single vessel, That vessel is simply called "the Ferry" and it is a pleasant enough little ship, well- maintained as befits its value to the kingdom. The ferryman is a jolly fellow, patient even with the youngest of his passengers. His young son helps manage the vessel and helps keep her shipshape.
If anything his family has a high place in the citizenry of the islands since without Hassan's family there is no way the kingdoms could be kept together, they would have no way of travel, no way of communication, no way of trade.
It was a ferry that would take around even the most humble of citizens of the lands... It didn't matter who they were. He was being supported by the kingdom, so he had no need to prevent them being able to travel.
He also knew very well that he and his family where the only ones that knew the way around the islands, and could travel the water safely. As he was surprised Alexander even survived the crash way back in KQ6. He would know for certain that any fleet without his help, could never make it through the waters.
Also there was no tourism industry to the islands with lands outside of the Green Isles.
As Derek Karlavaegen states in guide and companion the island was unknown, it was entirely romote and isolated from the outside world. The royal family made sure it wasn't known, and kept a secret to the rest of the world. That way outside world would not be able to influence their world. Derek made sure he kept his mouth shut when he got back to his home as well, lieing if need be, in order to hide the kingdom's existence.
Also its not just a ferry it is the Royal Ferry, they are the royal mariners.
According to Derek Karlavaegen in his article about the world written sometime after the events of KQ6, when Alexander is king of both Isle of the Crown and the rest of the Green Isles, ruling from Emerald Throne in the Castle of the Crown;
This island is home to the lands main source of transportation and commerce, a single ferry boat that has been run by generations of royal mariners. As long as the ferry is in good repair, all commerce and trade goes well.
Let's see if he is the royal ferryman of the land of the Green Isles and is receiving support from the castle to keep his ship in tip top shape so that citizens can get around the Islands, and now he's collecting money on the side... Well he's definitely gone greedy.