> You could just document the behavior that makes them want to fire them ("you smell funny") and followups in an email, and call it a day after a week or so.
Documenting something that has no objective criteria does very little to defeat even slight evidence of another motive for firing where the proferred reason is purely pretextual.
> Having success criteria when you just want to get rid of someone means if they do succeed, but you still wanted to just get rid of them, you are worse off as an employer
That's true; that cost is weighed against losing wrongful-termination lawsuits.
Also, very often formal PIPs follow undocumented informal ones that have the same purpose in reality that a formal one does on paper (but which avoid any adverse record for an employee you end up keeping), and the success criteria in the formal PIP are things the manager knows (to a fair certainty) the employee will not meet based on the informal one.
Documenting something that has no objective criteria does very little to defeat even slight evidence of another motive for firing where the proferred reason is purely pretextual.
> Having success criteria when you just want to get rid of someone means if they do succeed, but you still wanted to just get rid of them, you are worse off as an employer
That's true; that cost is weighed against losing wrongful-termination lawsuits.
Also, very often formal PIPs follow undocumented informal ones that have the same purpose in reality that a formal one does on paper (but which avoid any adverse record for an employee you end up keeping), and the success criteria in the formal PIP are things the manager knows (to a fair certainty) the employee will not meet based on the informal one.