I know when we see a job opening requiring a Masters Degree and a laundry list of skills and 5+ years experience for only $30k, the first thing everyone thinks is that HR is out of touch and out of their minds with regards to the market, but it's quite worse than that and many miss the main reason.
I've worked in the staffing industries for over 20 years now, I started as a recruiter after the tech bubble burst in the early 2000s and low level IT guys like myself at the time couldn't find IT related work, though I'm now a business intelligence reporting engineering for the industry working for an incredible company and amazing coworkers and leadership.
Before a company can hire an H1B employee, it has to prove that no citizen's are capable of doing the job and they can only fill the position with a non-citizen. So by posting the job for a set period of time and then showing that they can't find anyone (because they know no one can meet the qualifications at their low salary point), they are then able to hire an H1B employee.
H1B employees will accept these positions at the absurdly low salaries because they often have no choice. Once a company holds that person's Visa, they can only work there unless another company is willing to sponsor that Visa and pay all the associated fees to do so, meaning they have an indentured servant that has to accept all and any abuse since they're unable to easily get up and leave for a new position. Though there's also a worse scenario for H1B employees…
Many (not all) are brought over through H1B agencies.
These H1B agencies are willing to sponsor, and then hold that Visa for these people they lure over with the promise of high pay and great jobs, but once here, they're forced to work for those low wages if they want to stay in the U.S.
So they have no choice but to be taken advantage of by these agencies and companies love it since they get the talent they want dirt cheap knowing they can't just up and leave for a better position anytime they like since it's not easy to find another company willing to sponsor their Visa, plus there's the added bonus that this person is contracted through the agency, so they don't have to worry about benefits either.
This all adds up to companies being able to keeps wages low for everyone since it skews the market rates, they have what amounts to slave labor and no reason to change the status quo.
So next time you see one of those job positing we all think are insane, just realize that there's a far more evil reason for it's existence.