Maybe not a bug, but a route with 300 demand on one way & 75 on the other way seems unplayable to me. I don't know if it's realistic, but it's really counterintuitive, & punitive to the player.
I can understand 20% difference in some travels(I remember that kind of level between Bamako & Beauvais in my previous GW3, migrations explain the move). But more seems really unplayable to me. Even if it's not a bug. And here, it's 300% more !!!