Okay. So all of the main characters are going forward, they're on their own quest, their own journey. So the main character is going to ask the driver to turn back because he wants to kill some monsters or help some random NPC? That doesn't make thematic sense. "Open world" can mean a lot of things. Semi open hubs where you do your business and then progress can be considered "open world".
I would never take past information about FFXV for granted. It was originally a PS3 game.
Noctis is a prince. He's obviously going to decide where the party goes at any time. The other characters basically "work" for him.