There's an often overlooked part that you could call the "extrovert factor." There's always plenty of coworkers that thrive in group settings. Some number, maybe most, middle managers are extroverts, and when forced to work the way the average minion does, they suffer. It's why they became middle managers in the first place. Their productivity suffers in isolation too, so when converted into a wage slave, they can't complete with less extroverted people. Unfortunately they're better situated to promote their own success, getting by in people skills while more competent people get screwed.

Extroverts also seem to suffer in productivity during WFH, even if they aren't managers. They are stuck in a situation that hurts their functionality, offsetting the statistics. If they actually broke down WFH productivity by job description, I suspect that the extrovert/introvert factor will be a huge determiner of productivity.

Optional office hours seem the best fix, but the corporate attitude of obsessively monitoring the workers to be sure they're not wasting time and therefore money is another factor that makes these companies want to favor their preconceptions. The confirmation bias kicks in and then we have to listen to them focus on it.