Due to skills or pay?

Ever wonder why we always have to hire foreigners to work in our construction sites? Ya..I always see non-Malaysian in the construction site, is it because of the pay or is it because of the skills? I wonder... The first fly-over in KK involved some Chinese form China to do the construction too, am I save to say that is due to skills? I still wonder. Actually construction workers need a lot of professional skills in handling heavy machinery down to painting. I'm including renovation too. When I was in Hong Kong, I saw the workmanship of the renovation in my sis' house, and it was awesome, they go down to detail. I can see straight lines of paint in between the wall and ceiling, instead of a blurry line or a not so straight one over here. I saw workers hanging on the wall to put up tiles in one of the building next to ours in Shen Zhen, and that worker is a lady! I don't see it here. As for constructing a high raised (about 20 floors) building, they can finished and open it in a year time. I wonder if we have that many skillful workers here.
I'm not sure how you can get qualify as a skilled construction workers though. There is this site that offer training and get you certified by 2010 in the related field, give you details of safety and also employment training. It is both useful for employer and whoever interested in getting certified in construction industry. How I wish we have such a site in Malaysia too.
Now I can safe suppose that once you've got the right skills, your pay will then be increase according to that, am I right?