I'm not sure I agree with that. Generally speaking, the biggest risk is a crowded room with out-of-control people. Considering many school shooters are former or current students as well, it's a real hogan's alley mistake waiting to happen with live people. There's a reason that people trained to shoot in crowded areas are very highly trained on picking targets and temperament control so as not to make a tragic split-second decision. Police, in general, are trained NOT to shoot into crowded areas, though they sometimes do and sometimes tragedy ensues.
But I'm not sure we have to agree on this. My point was that *they are not apple-to-apple comparable scenarios. *I think I have shown this fairly well. You're describing some very specific tactical training (that teachers may or may not be receiving) that clearly depict the differences. If I owned a small store in a small town where only one or two customers are in the store at a given time, it's simply a different scenario even if you think it's more dangerous. If I live alone, anyone forcing their way into my house at night is a definite risk. No false positives. That leaves out some legal complication (which I might actually agree with you on), but the point is depicting the differences.
As far as preventing terrorist incidents, this is literally the point of terrorism
So you do not believe the "terrorism" variable is different in any way between a school shooter and someone coming to murder you for a gay pride flag?