I seem to remember the guy in Carmel took down a kid who was already shooting. I'd like to see the other countermeasures you mention put in place as well, but that doesn't eliminate the utility of metal detectors. Referring to Carmel again, that kid had a specific target. The presence of metal detectors might have been enough of a deterrent for him as he wasn't after just anyone, he was after a particular girl.
If they'll just move on depends on their motive. School shooters from within the school probably aren't going to go down to the mall or movie theater instead. Terrorists certainly could elect to.
Have to wonder how well connected the wand vendor is.
Not in Indiana Public Schools you won’t, unless we can get the law changed.School's choice. I'll stick to my hand held metal projector for self preservation.