The mistake you are making is assuming there are always citizens available who are qualified to do the job AND are willing to work for wages the employer can afford. STEM college is hard and many Americans do not wish to go through a curriculum such as structural engineering which has the highest flunking rate.
> assuming there are always citizens available who are qualified to do the job
What happens in a non-insane society is that they train people to do the jobs that need to be done.
> AND are willing to work for wages the employer can afford
If the employer can’t afford the prevailing wage, he doesn’t have a viable business. This is a borderline pro-slavery argument. It’s certainly pro-indentured servitude, unambiguously.
> STEM college is hard and many Americans do not wish
There are plenty enough Americans who would be perfectly happy to do so IF they did not know in advance that their own government would be deliberately sabotaging their ability to earn a fair wage, for their entire career. STEM is not more difficult than many other fields.
The arguments you are making are moral abominations predicated on the assumption of zero loyalty whatsoever to your countrymen, as if they are freely interchangeable with any foreigner who happens to present fraudulent credentials.