I've had the discussion several times in the past with different managers, and it keeps coming back to "person in chair" as a metric for whether work is being done or not. It's always a matter of trust, or lack of it, that an out of sight employee is getting work done. I don't think that argument has any validity. If you don't trust your staff to actually do their job you have bigger issues, and if you can't measure them any better way than whether they're sitting in a chair in an office, you can't measure them at all (person-in-chair time does not correlate with productivity in my experience).
