If you read the Screen Actors Guild rules regarding firearms on the set, any day there are firearms to be used there is to be a safety meeting prior to shooting or handling firearms. Anyone who will be present during filming, even if they will not be handling a firearm during filming- must be present, as well as the armorer (who is to control the safety meeting) and have the opportunity to handle any firearm to be used that day, familiarize, ask questions, etc.
Does anyone really think Baldwin attended said safety meeting that day? I doubt it.
Does anyone believe said (required) safety meeting even took place that day?
I doubt it.
All the rules were in place. They just weren't followed. As is the case in most firearms accidents/ mishaps.