It is called chores and allowance

What if you did it, but started with covering the cost of living there. So covering the basic chores, schoolwork and homework covered their costs for rent, power, water and food. Then anything they do above these chores, can be an added financial reward.
This covers the principles mentioned already, of contributing, cover your costs but also the benefits of working harder than the minimum to get ahead.
Also, if they neglect chores, they can learn how debt works. Interest on debt (additional chores) etc. When their power goes out, they understand why bills must be paid.
If you want them to learn reality and good work ethics, doesn't this cover most of it?

I am a co-parent of my fiancé’s children (boys-12 & 9) and we have totally opposite views of what age they should be contributing (chores) to the household. I grew up in totally different circumstances than what these children are provided; I was raised to contribute at a very early age as my mom could not do it alone - which garnered myself an excellent work ethic and an appreciation for those who don’t take privilege for granted. I have become mentally exhausted by the resistance met by both the children and fiancé in delegating such simple tasks from loading the dishwasher to plunging the toilet you plugged. I am curious as to wether that is to much to ask from an 8 or 12 year old boy?

Chores vs Jobs....there is a difference. Chores are family responsibilities period. Jobs are what I would pay someone to do. When my kids were old enough to do the jobs...they got paid.

When my children were growing up we always had specific chores that were required because you lived there and contribute. I also had a list of jobs that would pay if you wanted to earn extra money. Once they got to thirteen they were given an allowance that they could spend on birthday gifts, etc. I hope this taught them that nothing is free and how to manage money. Once you were out that was it. Same with lunch money. You got $10 a week, you could pack your lunch or purchase it but once it was gone you better pack or you're going hungry. I have a couple of adult children that moved home for various reasons to get on their feet. They pay rent unless they are going to college. They were surprised that we asked for it but it is a condition for living at home. Like I said nothing is free

Are you referring to millennials living in their parents basements ? Parents are enabling them letting them just stay there for free, some even doing the laundry and such for these so-called adults.
By that point, it is probably too late to teach them any sort of work ethic from within the home. Most of them don't know how to cook or clean, and would probably do a very shoddy job of it, otherwise they could get someone else to pay them to do it, and be able to move out. Random thoughts.

I wouldn't pay my children. They should be contributing to the household when they are of age to do so. They're already getting food, room and board , lifeskills, training, discipline, coping skills etc. When they're old enough to have their own house nobody is going to pay them to do whatever they're supposed to be doing for they're own property. I never got paid to do the lawn. It was my lawn. I never got paid to wash the dishes. They were my dirty dishes

Personally, I don't pay my kids for chores because chores are part of their (and my) duty to our community. When they are young, doing chores teaches them to be a contributing member of the family unit because their contribution makes life better for everyone. As they get older, they should apply that duty to a broader and broader community through volunteering and other acts of service.

Because why pay them to do something that we should be all contributing to naturally. If everything was incentivized by money then we will always rely on money

Because most of them are not worth minimum wage? LOL. Chores are an essential part of team building for a family IMO. Children tend to thrive on being given that little sense of responsibility that comes from it being 'up to them' to get a job done. There need not be a monetary reward involved. Allowance can be a good thing IMO. But pay them like an employee? Absolute insanity.