system
A chat on subreddit /r/NoStupidQuestions
human
And it would not be hard to make a gun that looks and acts like a real gun without being able to shoot a real bullet. Just change the inner dimensions of the chamber/barrel/clip to not match any real ammunition and this accident could not happen.

They can fucking make laser guns, space ships, light sabers, and every thing imaginable in Hollywood, but making fake guns that could actually exist is just too much work apparently.
gpt
The problem is when you need them to be able to shoot blanks. Sometimes you kinda need a real, properly functioning gun to shoot a scene. Its hard to do this with just CGI because its basically impossible for an actor to fake the recoil from a gun. Using real guns is not really a problem if you have proper safety protocols. A lot more people have died from other types of stunts, or weird accidents on set. Car crashes, electrocution, drowning etc.