Yes they can, but I have always SMH at the bias of the calls toward the defense

Absolutely make the call against the defensive player when he comes into a tackle leading with the crown of the helmet, and/or goes at the ball carrier's head. But, we have seen many times where the ball carrier lowers his head at the last moment, after the defensive player has committed to where he is aiming the tackle, and the defensive player is called for targeting. There should be more emphasis on stopping the ball carrier leading with his head.