Super Duty Super Crew

Why can the Super Duty Super Crew cab back seat floor not be the same as the F-150? Can the back seat of all the trucks be the same? I would like the idea of the F-150 hidden seat support in a Super Duty for the floor space if the back seat is lifted out of the way. If I remove the Super Duty lock box under the back seat then the seat support still hangs out in the way of the floor space.