My bet is that companies are hiring H1Bs but must post jobs. I literally dont see americans getting hired at well known tech companies
My wife a couple years ago was at a cyber security company that had very generous referral bonuses. Multiple members of senior management in her company were laying off talented and hard-working American citizens on the justification that they needed to downsize. But then just months later they would change their tune and fill the vacated positions with friends or acquaintances (always non-American citizens), they would also collect a generous referral bonus (often $20k or more). I'm not sure if this was purely to collect the bonus, because of ethnic preference or a desire to help their friends/family migrate from India but something strange was certainly going on. My wife eventually was part of one of these cycles of layoffs "because of the financials" then later heard from a colleague still working there that her manager had shortly afterwards backfilled her position with a referral of his own. Last we heard it sounded like the company was approaching bankruptcy.