To a certain extent, the focus on the 'sanctity of the head' in both codes are vastly different. The way NFL has evolved with helmets, padding, etc., is that many players actually use the helmet as a a weapon, leading with the head to drive into another player. To this extent, they are more 'fearless' about the use of the helmet because of the protective factor. This protective factor, of course, only goes so far, as you can get massive injuries with harder and harder hits. You would rarely see the same approach used in AFL, because with an unprotected head, it's, well, stupid.
