This is a pretty shitty article.
> Take doctors and surgeons. Women earn 71 percent of men’s wages — after controlling for age, race, hours and education.
> A pharmacist who works 40 hours a week generally earns double the salary of a pharmacist who works 20 hours a week, and as a result, the pay gap for pharmacists is one of the smallest.
These two quotes reveal that "controlling for hours" means "calculating per-hour wage", i.e. the underlying assumption is that the wage should depend linearly on the number of hours worked.
Which is obviously not true. Take finance, for example. If you're not willing to work 50, 60 hour weeks, you won't just get paid proportionally less; what will happen is that your career will stagnate, you won't get promoted, or might even get fired!
Also, personally I definitely want to be paid "disproportionately" for all the hours I do outside my "normal" working hours - after all, I want some time to enjoy life as well!
The final suggestion in this article is that workers should strive to make themselves as replaceable as possible. But this is, IMO, the worst advice possible; it won't have the effect of "averaging" the wages to make them more equal; instead, the best performer's wages will be pushed down to match the worst performer's wages, as it will no longer be possible to differentiate workers by performance. Brave New World!