I mean, they can just hire two people and have them each work three days per week at the same job. At 8 hours per day that is 48 hours work, and the quality will be better than one employee who starts to get worn out by the end of their 5-6 day workweek. Better coverage for vacations and sick days too if you have a work doppelganger who already does your exact job.
Of course, they will cut your pay down commensurately and we will have to figure some way to cover the other non-salary costs of the extra employees (healthcare, office space, etc.), but work-life balance would certainly be massively improved.
But if you do still need extra money, you could easily find a second 3-day job during your free days, possibly even the other half of your existing job!