Crappy jobs shouldn't have to exist just for the sake of desperate people being able to have one. A justice issue demands a justice solution, not the scraps that fall from the table.

See also: the current argument raging around minimum wage in the US, and whether the the millions of grocery-bagging and burger-flipping gigs are supposed to be something you can actually survive on, or are they just meant to be short term jobs for middle class teenagers who have no dependents or living expenses to cover? Or maybe we don't love this reality but there's nothing anyone can do about it because The Market has declared that these jobs are worth less than a living wage so whatever (obligatory FDR meme: https://imgur.com/gallery/SvuwZrm).

Yes, washing clothes was a crappy job, just like coal mining was/is in certain parts of Appalchia. That said, it was an important and necessary job in its day, and it generated valuable income for workers with no other useful skills. Removing crappy jobs and the income they generate is rarely good for the laid-off workers, especially in the absence of any social safety net. I wonder how many laundresses became washing machine mechanics, or laundromat owner-proprietors. I'm guessing the answer is "not many."

I'd certainly agree that both coal miners and laundresses deserved better wages and working conditions.

Absolutely, but of course "better wages and working conditions" has a time and place element to it as well. Coal mining conditions were obviously terrible in hindsight, but my impression is that they were considered "good jobs" at the time, with union protection and so on (depictions in media like October Sky notwithstanding).

In any case, it appears that the purpose of this human-powered laundry machine is not to put anyone doing laundry for pay out of work, but rather to allow some combination of doing laundry at home cheaper, faster, or with less physical strain (a crank may be more ergonomic than being bent over a tub, and your hands don't have to be in wet soapy water the whole time).