Simple: Tobirama wasn't pierced through, he was stabbed. (with the rod left inside his body)
Simple: Hashirama wasn't pierced through, he was stabbed. (with the rod left inside his body)
also simple: Sakura was pierced through - meaning that the black rod wasn't stuck in Sakuras back/front or any other part of her body. therefore Madara couldn't control her.
you're only immobilized if the rods are stuck in your body... they work as an antenna which makes Madara able to control your body like a puppet, but the rod on Sakura went straight through.
wouldn't it be ridiculous if Madara would be able to immobilize everyone whose been cut/pierced with the black rods? he could just make the black rods into pistol bullets and shoot everyone and then control/immobilize everyone in the Shinobi Alliance xD