Seems you think that a 4 day work week is paid as 5 is currently. I don’t see why that’d be necessarily true. In that scenario, it’s kind of like a part time worker and I can see many businesses finding appeal in that.
It should be. Most people won't accept less pay even if it comes with reduced hours.
If I remember correctly, a few pilots in the past highlighted there wasn't a drop in output, but it remained the same or in some causes increased.
Most likely the bottleneck in those were elsewhere. It was mentioned that they reduced meetings and other time-wasting overheads.
optional 4-day week with lower pay for the employees that want it = ok
employer-enforced 4-day week with pay equivalent to current 5-day week = ok
employer-enforced 4-day week with lower pay = not ok
Cost of living doesn't magically drop 20% just because you're not working that 5th day.
Nobody living at their cost of living is in the ballpark for a 4-day workweek in the near future.
Or slightly less due to having to spend more time on overhead and reading up on things. There is a minimum amount of time you have to spend just to be ready to do your job, many current jobs are so poorly managed that most of their time is spent that way.