'Norms' in quotes because they change like the winds...

Typical because the Armed Forces have to respond to those changes in some fashion lest they imperil their funding. Typical also because in every war, we have modified the rules, the doctrine, to cope with what the bulk of Americans want -- or seem to want, not always the same thing -- the forces to do. The US has most always tried to minimize civilian casualties and in recent wars, that has been at some cost in own casualties. In the most recent, that cost has been relatively small. We have also further modified at the end of or after after the wars to remove what may seem to some an excessively violent approach to operations (That lasts until more violence seems prudent...).

In this case, an odd combination of R2P and current 'COIN' theory sends us to combat (which is barely coordinated chaos) and demands that no one not positively identified as hostile be bothered, much less harmed. Thus the Pam is a fairly logical result of that anomaly. Like most such efforts it truly means well but suffers from excessively idealistic intent coupled with a lack of current appreciation for the harshness of heavy combat in which excessive concern for civilian casualties will cause a more significant increase in own casualties that (as has not been true in the current wars) will go beyond what the public and the politicians will find they are willing to accept. In mid to high intensity combat, it is inevitable that civilian casualties will be incurred and that the rate will rise with the intensity of combat..

The bad news is that such contradictory and untenable doctrine will get combatants killed unnecessarily as they attempt in many combat situations to avoid civilian casualties and find that is not possible without significantly increasing own casualties. The good news is that after a few weeks of heavy combat, reality returns and such idealistic but unrealistic stuff falls by the wayside.