EDIT: To give context, I'm a software engineer.
Similarly, talking to coworkers, even (especially) at unrelated parts of a company can be super valuable, even if it codes as “unproductive time wasting”.
TLDR your definition of work might be too constrained.
What should be allowed is to work as much as you want and get the pro rata of the full time salary
I'll let people waste their lives in the office and enjoy the world, if I could get the monthly equivalent of a min wage in my country while working one day a week I'd do it, call me a slacker if you want
The most typical example I've seen, are gov. / state jobs where one person was basically working 150%. Then they created an extra position to offload that worker, and suddenly you have two workers with 75% work. And if it turns out they miscalculated the need, because maybe the new worker is much faster / more efficient at their task, said worker is now only working 50% of the time.
Same goes for inefficient workers. I've worked with people that had zero knowledge in how to automate tasks, and would spend a whole day doing stuff in Excel, which could be automated to just seconds. No need for VBA, just basic macros would do the trick.
it's also peculiar in my opinion to point out worker laziness without apparent recognition of the worker-employer power dynamic where wage theft vastly outweighs so called time theft dollar to dollar
I don't disagree with you necessarily but the people who game it now, will game it with 4 day week as well. Slackers are always going to slack. 5 day or 4 day.