Many of the overhead costs scale as a function of headcount irrespective of how many hours each employee works. For example, let's say you work in a regulated industry where each employee needs to follow a certain training every year. Having twice as many employees each working 20 hrs will double the training costs. Management overhead will also go up since there will be more one-on-ones etc.

There are some issues that I think would make this difficult to do:

  - Two employees at 50% salary and time are not equivalent to a single employee at 100% of salary. They're strictly worse if always run in series, all else being equal. Alice starts project X on Monday and Tuesday, and hands it off to Bob on Wednesday because it's urgent. There's some inefficiency there. Good management could help avoid it, but would be hard-pressed to prevent it in all cases. At best, it's one more thing to worry about.

  - There are benefits outside of your salary that are more difficult to cut in half. Health plans, headcount taxes, etc.

That being said, there are some experiments being done (not at 50%): https://www.amazon.jobs/en/landing_pages/part-time-tech

Ok, I see. I guess if company feels that the talent is very valuable to them, it's possible to negotiate special terms like this, but I guess in general companies are not then interested in part-time roles yeah.

I'm actually planning to cut my time in half, but keep the same pay. My story was discussed here on HN yesterday/today: https://news.ycombinator.com/item?id=27133376

Long story short: As the startup I'm working at doesn't have enough money to raise my hourly price, I'm now proposing to cut my hours in half, but keep the pay. So I'm working half the time, but keep the pay. It's summer now, so I'm happy to spend more time with friends and family.

And while we're talking about working less, another thing that's interesting I think is "4-day work weeks". There are remote companies who work 32h per week. I even made a list of the ones I know, but I'm sure there are more: https://remotehunt.com/remote-companies-with-4-day-work-week...

Aside from fixed costs and aspects like coordination efficiency, companies have to raise pay more than linearly to get people into high hours jobs. Those disproportionate gains should be given back at cut hours, but too many employees would claim this is unfair.

I wrote about this a while back: https://www.growwiser.com/2011/11/27/less-work-for-less-pay-...

there are costs to employing someone that don't vary with number of hours worked.

The person you're responding to wants 100% of their current healthcare plan but only half the salary/expected hours, for example.