I think you may be confusing work with "work". It's easy to find yourself spending 40 hours in an office and accomplishing 6 hours of actual work, and conversely it's easy to spend 25 hours at home and do 20 hours of actual work.

This obviously depends on what the work is. People whose job is to focus on building things for hours at a time have very different optimal work environment from people who meet with and coordinate other people in short bursts. So no one-size-fits-all top-down policy can be effective; local flexibility is required.