I believe it’s right for working adult children living at home to make a reasonable contribution towards their keep. It teaches them about money and the need to budget in the big wide world. Whether that is returned later or not is immaterial.
When I left school at 15 my mother asked fir 30% of my wage. I was also expected to pay a bit from my Saturday jobs which I did from 13. I left home finally at 17 (4 years before reaching adulthood) and paid all my bills fir rent, food, travel to work, energy, clothes, everything, without expecting or being offered financial help from anyone. Despite being frugal, every week before pay day the meters ran out and if it was cold/dark had no choice but to go to bed, even if it was only 6 pm. Sounds hard, and it was, but I managed, learned from it and apart from a mortgage, have never been in debt.
I had already worked for 10 years before many of our adult children have even begun to think about looking fir a job. Our children, who are adults at 18, many of whom have had opportunities of education and travel, things I could only dream of, expect and are given a lot from us parents/grandparents which in the long run delays the time when they are forced to accept responsibility fir themselves. I am glad fir them and really don’t want to seem harsh, but as a starter paying a bit towards their keep is surely not expecting too much.