Dave I agree this is obviously a very complex issue. The supply/demand curve is a simplification.
Personally I think people overuse these kinds of simplistic mathematical models of the economy. It is one of the things social demcorats like me dislike most about the neoliberal side of politics.
Yet there are so underlying truths there we cannot entirely ignore. The tech industry is complex with need for a lot of very specialized people. People are not easily interchangable. A shortage of one kind of expert can really hamper the expansion of the business in another area.
Thus I think you are right that in specialized fields like this you can often see immigration help grow industry and give more job opportunities even for locals. But you have to consider that the tech industry almost always have a shortage of labour. Getting people educated in these highly specialized fields and getting the correct experience is not something easily done. That means there tends to be a lot of shortage of workers.
I see that in Norway as well. Despite getting a lot more software developers from abroad, there is still major shortage. I remember taking an iOS developer job once, where they told me they had spent over a year trying to get a guy hired.
The things is that most poor developing countries are not pushing out enough engineers and software developers to drown the market in the rich world. So judging the effects of immigration by looking at labour markets of highly specialized professions is wrong I think.
If you open up borders for free immigration, what you will see is a massive influx of unskilled labour. The world doesn't have shortage of unskilled labour. One unskilled worker can often easily be swapped for another. Thus in this case the primmitive supply/demand curve I showed does really matter. You get much closer to that kind of theoretical situation.
Keep in mind that most Western European countries actually have no immigration restrictions on skilled workers. If you are a software developer or engineer you can apply for a job in Norway from pretty much anywhere in the world. Getting an resident permit afterwards is a pure formality.
So high skilled labour migration isn't really an issue. We already know that open borders for skilled labour isn't a problem. We have had those border open for decades. But there is a good reason why borders are NOT open for unskilled labour. That has far more dramatic consequences, which is what I focused on in my story.
