Notice that this automated turret has not been programmed to distinguish between armed and unarmed people, merely between people and trees. So, there's no chance of a mistake - it will work as intended, shooting at exactly everyone that approaches. I doubt anybody would ever bother with a turret that gets more sophisticated than that, as that would defeat the point - you set up such turrets in places where you don't want even your own people to be (notice this is the Korean border we're talking about). In places where there's a chance of a mistake, you'll put ordinary people. It's just like the Berlin Wall - East Germany didn't set up the wall with all of its defences in order to filter the bad refugees from the good ones, but to be able to kill them all.