Artillery isn't typically used to do infantry jobs. We call that a "war crime". Unless it's us doing it, then we call it "collateral damage".

You are correct, most bullets fired in an infantry engagement do not in fact hit their targets. Assuming a target can even be seen. Bullets are cheap and useful for all manner of things, such as keeping the enemy's head down long enough for you to get into position to use a few bullets and kill him. ;)