Whenever I see statistics like this, I always wonder “how” and “who” is defining the performance being studied.
In my experience I have found very few occupations where performance can be quantified like a machine stamping out widgets.
I’m sure the “naughty librarian” pharmaceutical rep that visits your primary care physician can account for every minute of her work day, but I wonder how much of that activity can be considered “work” defined as a physically or mentally taxing expenditure of effort.
It is true that it is hard to quantify “work” in many of today’s jobs, but companies can start by reviewing online activity of employees. In my job some people openly socialize for hours each day; we’ve become a “post-work” economy for many.
I think that's the wrong definition of "work". I think a better definition of "work" would be time actually engaged in carrying out the business of your business. Your pharmaceutical rep might spend most of her day driving from one doctor's office to the next, and the rest of her time flashing her boobs and nattering about the supposed benefits of her company's product. Not sure it's mentally or physically taxing, but it's definitely "work". It's what she's being paid to do.