I've worked on employment litigation in several industries (white and blue collar), they are everywhere.

Defense usually wins if they have good documentation of putting employees on a PIP, even if the reason is obviously dubious*.

Maybe I'm cynical because I've only seen it in a lawsuit context, but if you're put on a PIP, start applying. There's no out.

* like, discrimination, company wants to fire long-term employee because of an injury, company wants to fire an employee for union organizing, etc.