It is the question. Do you agree or disagree that you must be a US citizen or a legal resident to work here.
Of course the answer is yes, you agree.
Now, how does an employer verify that and who is responsible for determining that status. By golly, its Uncle Sam.
OK, so how does Sam determine legal status? It can be a birth certificate, I suppose. Or a sworn affidavit from relatives I guess. Or they can use a SS#, which every ciitzen is assigned either at birth or upon legalization.
Is there potential for abuse? I suppose. Do you put in safeguards to mitigate that, of course.
No matter how you slice it, a person being present in the USA does not qualify him to work. He must be legal.
And the privacy you mention does not exist. You pay taxes. Sam knows what you make and where you work. You get a license, Sam knows where you live. The system is not to tell YOU that you cannot work. It is to tell miguel from Mexico that he cannot work.
How can you enforce existing laws if no one knows a persons legal status?
The federal government has NO business forcing Americans to get permission from the Department of Homeland Security in order to work.
Combating illegal immigration does not require such a loss of liberty and privacy. And believe me, this would be an unprecedented loss of liberty and privacy. Go ahead and read the link I provided for some of the legitimate concerns raised (and it barely scratches the surface).
How can you enforce existing laws if no one knows a persons legal status?
You act as though the existing system has never identified an illegal immigrant. And yet, employer crackdowns manage to make the news now and again. The only thing that prevents their broader success is the policy of G.W. Bush, under whose leadership the crackdowns decreased.