> What might look like low performance in a corporate environment can just be someone setting boundaries and refusing to let work infringe too much on their personal life.

Another is poor fit between the employee and the job. One the lowest performers in a role can sometime be a great in another because they do/don’t care about clean code, long hours, spelling / grammar issues, minor aesthetic issues, minor bugs, speed, etc etc.

The universally perfect employee basically doesn’t exist as much as organizations want everybody to be interchangeable cogs.

Or the fit between employee and manager. I've come into many teams where the employee on a PIP went to being one of my best performers while those I was given the ravest reviews for were just mediocre under me. Or even just cultural. I had to change how I managed/my expectations as I moved positions around the country or when offshore teams were brought on.

I agree with your shocking premise that people are not machines and expand it to include that they are also not numbers in a spreadsheet or HR system.