> Doesn’t that tell anyone that there MIGHT be facts or at least good research on this that it isn’t producing good work for the money?

I'd wager that most people are just as productive or more productive when WFH, but there will always be unethical people who will abuse the privilege when given the chance. There are tons of anecdotes of people just being straight up lazy, defeating naive monitoring solutions with mouse jigglers etc, or committing fraud by working multiple full time jobs concurrently.