In basic economic theory, high wages mean that there's insufficient supply. So I wonder why don't the "truly unemployed" people learn whatever the market rewards and compete with the highly paid workers.
If it is because they can't for whatever reason, 4 day working week doesn't solve anything.
(Genuine question, I'm not making some kind of a right-wing point.)
Because learning involves being effectively unemployed for multiple years, and is only available to those who did well in school. Then, on the other side, you're still not guaranteed a job. Add to all of that the fact that you'll probably have to move and effectively restart your life elsewhere.
My fiancée is currently in the middle of this. I don't know if she would've been able to go through it alone.
A homeless person usually isn't able to learn what is needed to become a neurosurgeon. So the issue isn't that we don't have enough highly paid jobs - it's that we don't have enough people able to do those jobs. Which makes sense, if everybody could easily become a neurosurgeon, it wouldn't be a highly paid job.
Some of the gains that have gone to the top need to be paid to spread the work over more people, a 4 day week would be a start.