For the US the biggest impediment is healthcare is based on a per employee charge, not per hour charge. So there's this perverse incentive to extract every possible hour of labor from an employee, even with overtime at time and a half, to defray another fixed cost.
Without public health care and the subsequent lifting of healthcare costs from employers back over to a progressive tax system, I can't see the 4 day week being widely adopted.
Without public health care and the subsequent lifting of healthcare costs from employers back over to a progressive tax system, I can't see the 4 day week being widely adopted.