It's not just different interpretations of the rule -- but different interpretations of "what actually happened" by different referees at different times -- and by different observers (as can be seen on this blog). A premise of law is that "justice must not only be done, but it must also be SEEN to be done". While this isn't "law" per se, this rule DOES originate from lawyers trying to circumvent legal and financial consequences. THAT, sadly, is what this rule is about.
This is NOT about "safety". No one has managed to define that as yet. Unfortunately you can't ensure (head/neck/body?) "safety" in the most violent sport in the world. You start trying to do that and you will inevitably transform the game of football. In essence it won't be football.
If the best athletes in the world don't want to play football (as most of us know it), they should compete in some other sport. To this observer, all players/recruits should be required to sign informed-consent waivers placing full responsibility for participation in the hands of the player. In turn, a player can purchase any number of different kinds of insurance policies -- and demand the best equipment. Currently the best technologies aren't being utilized.