Offering that sponsorship has very real costs to the company, well into the thousands of dollars per year. It seems perfectly reasonable to me for the employer to deduct that cost relative to what another employee who doesn’t bring those additional costs.
How much? I have a friend who just got their green card after 10 years of working at the same company. Based on the experience of others in the same situation, they estimated the company would require them to repay 10-15k in expenses if they leave immediately (they're required to stay for two more years before the company will waive the full cost). I take that to be the employer's actual immigration sponsorship cost.
If the employer were to deduct that cost from their salary (ignoring the fact the employer could be repayed in other ways), it would have amounted to about $1,000-2,000/year, which is not a level of underpayment I think many people would make much noise about at software developer salaries.
I think using sponsorship costs to justify underpaying immigrants is just a convenient excuse.
We can argue that perhaps the visa was worth the extra money (and for those people, it certainly was), but it's still pretty crap. I'm sure wherever the rules allow it you will find companies (even well known ones) trying to save money in this way.
Edit: to clarify, I've checked and either the employer and the employee can bear the financial burden of the I-140 and I-485 filings, depending on the agreement. But the PERM labor certification costs must be borne by the employer and cannot be recovered from the employee, nor can immigration status be a basis to underpay them aside from recovering the permissible costs on a one-time basis.
For the employee the situation looks more like this: https://rachelbythebay.com/w/2018/09/08/visa/
The government might as well collect that surplus as tax.
Let me fix that for you:
"Purchasing that slave has very real costs to the company, well into the thousands of dollars per year. It seems perfectly reasonable to me for the owner to deduct that cost relative to what another freeman who doesn’t bring those additional costs."
Remember the immigrant suffers additional liabilities and risks a citizen wouldn't. The employer in this case is in a much more powerful position to keep the employee in line.
Many, many people cannot afford to lose their jobs because they live paycheck to paycheck. Funny how they're never called slaves or referred to as having owners.
Some slaves absolutely sell themselves into it, in other to escape poverty, debt, or war[1]. It doesn't change the fact that they do have less rights, less options, and their employer can and will abuse this as evidenced by this thread and a shitload of other HN threads. (and yes, I understand this is unpopular sentiment because the citizens want to believe they are doing a good thing and providing upward mobility and the immigrants don't want to consider themselves slaves)