No, my logic is not flawed but your TV "logic" sure is. Your Escort was probably produced before regulations demanded that rear belts, or approved mounting points, were mandatory, as in my Cortina GT and 1600E of the late '60s period. Carrying of passengers in that area behind the extended cab pickup's driver is not permitted by law in Thailand. That people use it for that purpose is beside the point.
If that rear space was designed to be used to carry passengers there would be seat belts provided from the factory (as required by safety regulations). That's why every car designed for carrying rear seat passengers produced for many years has rear belts, or the provision of approved fixing points. Extended cab pickups (not double cabs) do not have that provision, that is because there's no reason for them to be provided, just as there's no reason to provide belt mounts in the rear tray of pickups.