Anonymity probably accounts for a decent portion of the discrepancy (meaning some of your co-workers would probably be anti-WFH in person, and pro-WFH anonymously)

We’ll, I can’t prove or disprove that claim, but most of my coworkers have always been very candid with their preferences. I find it difficult to believe that there’s a large number of people who regularly say one thing while secretly believing the opposite.