A bigger population just hasn't been trained properly. We have no controls for that, so people get lucky with disparate learning being just enough for their first job, then that turns into experience towards the next job.

Then they find themselves among high performers and can't keep up, really through no fault of their own.

Some high performers are just natural and born with it, which is unfair to let that affect how anyone judges others' performance, but it still happens too (esp. if the high performer is doing the judgment).

What I generally see when people categorize their workers into high/low performance is from a bigger issue of poor stewardship over the industry and training its talent.

This means I don't actually have to improve, I can instead just spam job applications and get lucky just because technology is such a large industry.