How can Microsoft justify making thousands of H1B filings when obviously there's no shortage, and in fact there is a glut, of software engineers? https://www.levels.fyi/h1b/?q=Microsoft&employer=Microsoft

It depends on the role, not every position is fungible.

Why do recruiters keep contacting me even though I’m retired?

> Why do recruiters keep contacting me even though I’m retired?

Maybe your retired flag hasn't propagated the system yet?

Maybe they're just casting a really large net?

Also, it costs them nothing and maybe they occasionally get someone to unretire.

Sure, and I may agree. But if there was a glut of engineers that would seem simpler for them.