Reminder that negligence is not automatically criminal negligence. If you aren't being careful and an accident occurs as a result, normally, you aren't going to be charged with a crime; the victim can sue you. For it to be a crime, you had to act in a knowingly and deliberately reckless manner.
So let's say we all agree, for a moment, that an actor should be following all the rules of gun safety. Even in that case, it is just common sense that it is less irresponsible for an actor on a set to fire a gun that he has been told is unloaded by one of the people hired for that purpose in the course of his job than it would be for Joe Schmo to forget to unload his gun, assume it is unloaded the next time he picks it up, and shoot someone while clowning around. Heck, Baldwin may not have known there were live rounds anywhere on the set.
In assessing negligence, context matters. You can't just say "the rules of gun safety are x and y, so everyone who violates them is the same." There are circumstances that will make the negligence more or less severe.
A young child should never be unsupervised. But if a caregiver is momentarily distracted while chatting with a neighbor and the kid runs into the street and gets killed by a car, that's likely not criminal. If a caregiver is passed out drunk and the kid runs into the street and gets killed by a car, it likely is.
