I believe alignment has a lot to do with it. (Obviously not all of it lol thousands of hours on the table might help too) But when your body is aligned to your vision then you don't really have to focus so much on aiming. Where ever you are looking is where the cue is pointing.
The better alignment one has, the less muscle is involved to compensate for poor alignment (rotating a shoulder one way or the other, twisting your wrist a few degrees to the left or right. All that can happen without even noticing it. That's why a lot of people miss on power shots. Muscles tighten and flex in the direction they're naturally aligned to which most folks aren't aligned very straight.
If you notice, the Ko brothers all have a similar stance. As do many other Taiwanese pros.
This is part of the equation. I talked to their translator for quite a while they played the turning stone classic a couple of years ago. She clued me in on their focus on training within a system. Not just the Ko's but all the Taiwanese players (Kevin Cheng, Chang jun-ling, etc) all share a relatively similar playing/shooting style. Compact stroke, alignment, etc...methodical use of the jump cue. They are all trained under the same system and I believe for pool, this accelerates the learning potential and results are felt from early on.
I remember reading during the Big Ko win at the world championship over Shane, that his father was there as a coach. So they are not lone warriors learning the game on their own, there is a lot of coaching.
Also, they play a ton for money- gambling high pressure atmosphere increases your potential as we know in America, but couple that with training and focus on fundamentals from an early age. The results are the Ko brothers.