It looks like you're assuming there's no salary elasticity in the job market, which is probably not accurate. There are always trained nurses that maybe decided to retire early, considered the stress not worth the pay and switched jobs, or something else like that. Higher pay can get them back on deck.

Demand for nurses doesn't change abruptly and before importing people became a fad it was largely followed by supply.

What profession doesn't require training or experience to do well? I wouldn't hire someone who had never built a house before even if I wanted one built right now.

You're right, you would look outside of your country's talent pool to try to find someone qualified to do it for you.

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.

Is my "local market" the entire rest of the United States? Or just my state/county/city? This still doesn't seem like you're describing a real problem.

It doesn't matter. You can define your market as whatever you want.

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.

H1B is not going to get you someone quickly either.