Why don't Terminators have perfect aim?

In the movies Terminators are shown to have extremely advanced image processing. They can do facial recognition from far distances and calculate a lot of environmental data. In Terminator 2, it shows what Arnold himself would be seeing and it was a red screen with a targeting system that was easily able to identify things like this:

So with the Terminator's advanced machinery and computational ability, why could they not have perfect aim? Wouldn't it be trivial to detect stuff such as humidity, gravity, trajectory, distance, angle, etc required for a perfect shot each time? Of course there is the unpredictability and reaction time of the target to move, but for shots of at least <50 yards I would expect >95% accuracy. I do remember one scene where Arnold showed off his accuracy by shooting a guard perfectly in the leg, and he certainly was skilled with a shotgun, but that's it.

Given the technology they possessed, is it really just to make the movie more realistic? Could it be limitations on the weapons themselves?

Answer

There are three things that would interfere with "perfect aim".

1. Damage. I forget how bad Arnie-800 was injured at this point in the movie, but he had taken some hits. Probably nothing that would damage the endoskeleton, but the external flesh would have big ragged holes in it and would compress differently (and in an impossible-to-calculate-compensation way) than it would when he was whole. Later, parts of him are crushed in heavy machinery, or banged up when he rolls away from crashing vehicles at 80mph. That's going to ruin any precision calibration that his servos underwent during manufacture.


2. We're taught in physics/calculus about ideal bullets taking parabolic paths through the air. But it's very idealized. You don't get perfect bullets, some come from the factory ever so slightly heavier than others. Ever slightly so more powder in the shell. The barrels have slight imperfections, and even slight amounts of dirt. Most of all, the very air itself isn't still. Good marksmen can compensate for wind (and no doubt terminators are even better at this), but this can change even after you've pulled the trigger. Not enough to make the terminator miss, but he'll hit a quarter of an inch off when firing from a distance.


3. He's not aiming at a stationary target. This means he has to "get a lead" on the target, you aim slightly ahead of where he is now, so that when the bullet gets there it hits in the right place. This is incredibly difficult, and (other than at point blank range) even humans can manage some unexpected and unpredictable velocity change after the trigger is pulled. Then think about how in his fight with the T-1000, it's an incredibly intelligent machine itself, randomly moving with inhumanly fast reflexes.

So perfect aim is essentially impossible. At least in warfare. On the other hand if he participated in the shooting events at the Olympics, it's safe to say he'd walk away with every gold medal they give out.