This could be due to regulatory requirements on Morocco's side. I regularly fly EUN<->TFS via LPA with Binter: In/out of Laayoune you have to take your assigned

This could be due to regulatory requirements on Morocco's side. I regularly fly EUN<->TFS via LPA with Binter: In/out of Laayoune you have to take your assigned seat, within the Canaries they don't care.