I'd imagine that they're unproductive because of the long hours that they spend in the office. It's been a source of mystery to me (European) how our offices in America manage to put in 60 hour weeks every week, often with a crazy commute before and after, and yet never seem to make fuck all progress on anything. Better to concentrate on how to be as productive as possible for time that you are there, than to fetishise the total amount of time?