Comment by cortesoft
If that was the case, why would they have to hide the job offer? If no American citizen is going to take the job at the lower pay, there is no need to hide the offer from them. If they are going to take the lower pay, there is no advantage to hire an H1-B.
Presuming we're talking about the job offers from the article, it's for PERM, part of the process for green cards, not for H1B. As far as I know, you don't need to post a job offer to consider local candidates for someone to apply for an H1B, only for them to get permanent residence.
Employee works for a company under an H1B, company likes their work, wants them to stay longer (H1B has a max of 6 years unless you sponsor the employee for permanent residence). Employee doesn't want to be in this weird temporary worker status forever (and again, after 6 years they'll need to), so the company has two choices: either hire a new employee, hope they've as good as the one you already have under the H1B, train them up to be as familiar with the job and its work as the H1B, and then forget about getting the existing employee permanent residence, OR, just sponsor them for the PERM process, put out a job ad with a really low likelihood of anyone applying, and move on with their lives.
The way the PERM process is set up, there's really no reason not to do the hidden job ad, it's not really regulated against, there's not much financial harm in doing it, and they already have an employee they like and who wants to stay, so for those two parties (and presumably anyone who likes working with this person, and any friends they have in America and so on), there's no reason not to just put out the hidden job ad.