Something you should understand about the 4-day workweek.
From the studies conducted so far we know it seems to increase overall productivity. Which means companies, or at least some, would make more money if they implemented a 4-day workweek. So then you may ask yourself: why haven't they? Don't they want to make more money?
Not necessarily. It all comes down to relative wealth. A 4-day workweek would benefit them, but it would benefit regular people more. And so the divide in wealth/power/quality of life would shrink. So technically they'd be richer, but they'd feel poorer, because we'd get closer to their level, even if by just a bit.