I have a friend whos a teacher and her attitude is "why should I have to also now protect and arm up added to all the other stuff we have to do. And we won't get paid any more for this".
She doesn't understand the concept that she is her own first responder, even if her armed husband is outside the classroom 20 yards away (Uvalde cop who was told to leave when his wife was shot inside, who didn't die until she arrived at the hospital).
Most people have a short-sighted attitude when it comes to emergency preparedness. That's what 911 and on-campus security and medical employees are there for. It's the "not my job" mindset. Nobody ever told your friend her safety and security ARE her #1 job -- that everything else is a lower priority because you can't do those other things if you're injured or dead.
We drill into teachers and students how to act in case of fire -- holding fire drills, doing Fire Prevention Month in Oct every year, and having firemen give talks about having home evacuation plans and "stop, drop & roll." Fire is taken seriously when schools are built, detectors and sprinklers are installed, extinguishers are located throughout, fire doors are included in hallways, and alarm systems are installed and tested.
Why do we do all of that when the odds of a fire threatening the school during school hours are extremely low? Maybe because someone in authority was convinced that the safety of our kids in school are a high priority, and that the cost for being wrong would be too high.
That same thought process needs to be applied to school shootings. What's the cost of being wrong about having armed and capable teachers if/when a shooting happens there?