The trouble is this calculus is being done at the local level despite the mantle of responsibility of management; the manager decides it is not worth their personal effort to lose a low performer, because they will generate more work for themselves. Meanwhile, the company suffers the net negative impact of such a decision - arguably even worse for the manager's career.

That's the main challenge I have coaching management folks - now you have the option of doing work, and often you'll be tempted to take the path of least resistance, but that'll usually lead you astray.

Edited to add - sorry I missed your net negative comment - to touch on that, as it's another thing I see often.. Giving up on the org's ability to satisfy your needs is another toxic pattern for management - it is a lose/lose essentially. Management is often in a position of needing to push for the things it needs and advocate for the people relying on them.

I can't speak to a US perspective but in the UK and some EU countries I've experienced, firing someone is incredibly simple.

In fact every difficulty I've seen is simply that someone didn't follow the clearly defined procedure.

It's literally written out for you. You don't have to think or care how you feel, just follow the process and you're done. If the process says someone should stay then you got something wrong. Simple as that.

As a mediocre person, this gives me comfort.

the answer is always yes but the org pays the costs not the manager, and the manager isn't accountable to those costs, and the manager IS accountable and vulnerable to political costs