Unrelated data point: Any commercial location in Israel over a particular size or capacity has security at the entrance with a metal detector wand and a pistol.
But it’s largely a joke. Wanding and bag searches are cursory. Anyone who wanted to could get a weapon past them. If implemented in the states (by hiring at minimum wage anyone who can get a gun permit, of course) can you imagine any way that would improve the situation, because I can’t, and plenty ways it would make it worse.