Why not use non-lethal force in these guns that are used in public places? Sure, nobody wants their child hit with a rubber pellets or knocked out with a tranq

Why not use non-lethal force in these guns that are used in public places? Sure, nobody wants their child hit with a rubber pellets or knocked out with a tranq because they held up a water gun (just random thoughts, could be many possibilities), but if the miss rate was small enough and the consequences for missing were small (non-lethal, non-life-threatening), they could definitely be used to save lives.