COVID-19 and consciousness about complications from WFH, new stresses or demands on employees in their family/home lives also ended up resetting the clock on a lot of PIPs or plans to set those PIPs in place ...

Also, managers/directors/etc often have to overcome the issue of reversing momentum on past praise or ratings given to these individuals.

In the Google perf (performance review) process, many individuals that probably should have gotten PIPs and/or counseled out also got high performance ratings in past reviews (for other reasons) from the very same managers and directors.

Generally to initiate a PIP, there needs to be a rating to justify the action (i.e. "Needs Improvement" - lowest rating). Giving a rating two levels or more above or below the last rating also requires justification in the rating process.

Google also cancelled/deferred its mid-year perf cycle during 2020 due to WFH/COVID challenges, which delayed opportunities for managers to give such ratings or feedback through the formal process. (for context: Google traditionally does "perf" twice per year, which are the formal opportunities for employees to receive performance ratings as well as nominations for promotion); this may or may not be correlated with interesting product launches or changes you might see as an end user during the year).

"Performance Improvement Plan"

The US is insanely litigious and most large companies are very aware of the cost of unlawful termination litigation. That means to actually fire somebody you need cause, and that means having an airtight paper trail which takes time to generate OR having the employee do something that directly violates something you've explicitly told them in writing they can be terminated for. You're not generally dealing with stupid people, and if they're obeying the letter of the law/policy even while defiling the spirit of it you really can't do much to terminate them.

There are other things you can do to make it clear they need to move on but it's usually way easier and more efficient to just directly negotiate a severance and have them resign.

I didn't say that. It's a complicated situation, right? If an employee threatens to kill another, they can be terminated immediately (with security escort).

i'm talking about employees who are in good standing, like Timnit was at the time. She had just been previously promoted. A person like this, even if they are annoying many coworkers through emails or papers, can't just be terminated because the manager doesn't like them (huge liability risk). Instead, Google (or IBM, or whomever) wants a paper record showing that somebody is unable to do their job, is put on a performance improvement program, cannot improve performance. At that point, Google can terminate the employee and if there is a lawsuit or mediation, Google has the paperwork required.

I think there are complexities with firing some people... If a manager just walks round firing people with little evidence, all other employees will live in fear of being fired. That isn't good for morale, productivity or creativity.

Instead, the problems of the to-be-fired employee needs to be abundantly clear to everyone nearby, so that when that person is fired, it doesn't have deep social impacts.

Combine that with desiring to fire someone when a replacement is trained up (often many months), and at the end of a big project (sometimes a year), and not just as management is reshuffling... And suddenly a firing takes 1.5 years.

A friend of mine, a non-technical manager at Google, similarly struggled to fire an obvious underperformer for over a year, so I totally believe it.