If you want to read through those industry guidelines and rules, you'll see just how serious these things are taken. Remember too that this is after the death of Brandon Lee while filming The Crow. In fact, you can read them here:
https://www.safetyontheset.com/resources/amptp-bulletins/
But honestly, you have to try to be this negligent and unconcerned with safety. Walk through this whole mess with me and you'll see what I mean.
So, the cast/crew takes out movie guns to go target shooting. While this is questionable, I might not complain too much although my guess is they didn't go to a real range of any sort. They were probably just walking off into the New Mexico desert and shooting at stuff. My answer would have been that if you want to go have target practice, go to a range, rent a gun and have at it, but movie guns don't leave the set.
But this means that someone brought real live ammunition to a set, which is the first red flag. You NEVER do that, ever. Next, they did their shooting and brought the gun back with a live round in it. Which means someone stepped back off the firing line with a loaded gun and didn't bother to check or clear it. Any range officer worth a damn would have pointed out this is a no-no. The gun comes back on set with real live ammo (violation #2 of the no real ammo rule) and the armorer does not clear it...again. This is her only damned job! She is responsible for all the weapons and ammo, including their safe storage.
The loaded firearm, at some point, gets left unattended and out of the armorer's gun safe and an Assistant Director grabs it (only the armorer is supposed to touch the guns according to the rules) and without checking it, declares it to be safe and hands it to Alec Baldwin. Baldwin ignores multiple AMPTP rules (which also include Col. Cooper's 4 Rules) points the gun at actual people and pulls the trigger, killing one person and wounding another.
If Baldwin had only popped off a blank, we'd have likely never heard a thing about it. But Baldwin killed someone because of his own carelessness and even worse, because the armorer on set was completely negligent. You quite literally have to try to be this careless with a firearm. A weapon that has the capability to end someone's life, and she couldn't be bothered to put her foot down and follow industry guidelines that have been in place for decades. Hundreds and hundreds of guns get handled in the business every single year without a single incident, and this lady has multiple negligent discharges on one set, one gunshot injury and a fatality. That ain't bad luck. You have to be so cavalier in your duties that you just don't care.