Or are you suggesting that you would wait around and be homeless for 4 years until someone local built up enough training and experience in order to build your house? If you're going to suggest that you would wait and "live somewhere else", I would point out that people who are trying to hire, for example, nurses, often don't have that luxury. If they wait 4 years, they'll be dead.

No one is suggesting that high skill work status are used for people with no training or experience; they explicitly require training and/or experience in order to qualify. If think you're proving my point; if you need to hire someone right now, and there is no one available locally to do it right now, then there is a shortage, and you need to look outside of your local market.

The point is that if someone you need to hire is not available, you're going to try to find them elsewhere. You're not going to wait 4 (or whatever number of) years for someone to go to school, train, gain experience, and be available for you to hire.