I'm confused because economically it doesn't add up.
Shortages of labor should lead to higher wages. Supply and demand.
So it would make sense to relax laws prohibiting working more than 40hrs in order to unleash additional economic output i.e. increase the amount of money made.
The article claims that for some reason that defies logic, it will just make employers demand more work for same amount of money.
I see two possibilities for that.
A country-wide collusion between employers to fix wages. That doesn't seem possible. If employer A has profit to spare and could make even more profit if he had more employees, what logic would lead him to NOT raise wages and steal workers from employer B? The wages should raise because workers would migrate to the highest paying jobs.
Or there just isn't profit to pay more in which case there's noting the government can do either way.