If the only way to detect this "fraud" is that VPNs are in use, then why bother returning to the office? Seems like it's only a cost center with no added benefit.

Control. The old guard of large business cannot stand that people have their own lives away from work and how will they know that someone is actually working rather than collecting a paycheck?

It is actually odd they perceive it like this. I work much harder from home than I ever did from the office.

It is impossible to hide doing WFH like one can do “endlessly” collaborating with your colleagues at the office.

Not odd at all. First-level managers may still have a tenuous grasp of being an empathetic person, but managers of managers are only interested in growing their kingdom. To that end, WFH makes it harder for them to demonstrate a need for more headcount.

Let me make it very clear: Employees that WFH are more productive, so you don't need more of them. If you don't need more headcount, the executive has no use. If the executive has no use, they will be executed (symbolically, as a re-org).

It's not odd, it's 50% incompetence 50% feelings of self-importance

there are countless ways to detect fraud, these days we leave digital footprints all over the place, I just gave one simple example how to do it in 5 minutes with 2 SQL queries

Or maybe just don't cheat because it's not ethical?