"Some years, international comparisons of GDP per hours worked have found, workers in Norway, Ireland, Denmark and even France, with their 30 days of paid vacation every year, their café culture, their generous paid family leave policies, their short work hours mandated by law and their new directive forbidding some employers from expecting workers to check work-related texts and emails after hours, beat us by a mile."
In other words,
In some years (not others), the GDP per hour worked is higher in countries where employees work fewer hours per year.
If people work 20% less and are 10% more productive per hour when they do work, they're still less productive in total than if they didn't reduce their hours.
Why does a company care if their salaried employees are more productive per hour? They just want that employee to maximize productivity over the employee's lifetime with the company.
If the article has only historical anecdotes to demonstrate that employees are more productive in absolute terms if they work fewer hours, that's not very persuasive toward the point the author is trying to make, that major industries and large companies should change because they get more value out of having employees work fewer hours.
I'm not saying I disagree with the author's point, only that they are using misleading evidence to try to support it.