>[...] I don't know exactly when real-world productivity got enough higher than P that we could realistically start reducing worked hours, but it definitely did so at some point in the last several decades. [...]
GDP per capita has been growing exponentially for centuries[1]. Is there some arbitrary GDP per capita level where people should be expected to kick back and relax? Why makes your arbitrary line more or less correct than someone else's arbitrary line? Moreover people's revealed preferences show that for most people, that line hasn't been reached yet. Why should people's revealed preferences be overridden by whatever number you came up with?
[1] https://ourworldindata.org/grapher/gdp-per-capita-maddison-p...
>If, instead, the surplus is captured by the wealthy, the workers don't see benefit, and inequality grows.
Economic statistics shows it hasn't been captured. Even if you're some sort of marxist that thinks labor's share of GDP should be 100%, at the very most this means the point at which everyone can kick back and relax is delayed by 40%.