The people who work 20 hour weeks are upset and certainly dont work any additional amount. Daycare probably booms as a business.
Productivity plummets to tremendously low levels, economies collapse, massive numbers of people die, etc.
Less than half of doctors work 40 hours or less. Pretty significant number above 60 hours/week. Same for nursing and much of the medical field.
Firefighters have very long hours.
Truck driving and logistics pretty much depends on truck drivers maxing their hours at around 70 hour weeks.
Lawyers pretty much cant work 40 hour weeks without the legal system collapsing.
So right away, we are going to have people working different amounts of hours per week. It's unavoidable. This alone means you can never have 'equal outcome' A doctor who works 60 hours a week and still paying off med school loans cannot have the same outcome as a part time mcjobber.
That's the failure of the progressive tax. The progressive tax is some wierd attempt to make the rich less rich but instead generates significantly more income inequality as a consequence.