I don’t think it’s fundamentally unfair.
There’s so many details that change it. Like does the higher earner want and find advantage in the part time parent working part time Or not at all?
I was a single parent for a gold while with mI Al input from the kids Dad. I built my career far more as a single parent than I did when I was with exh.
Now the kids are older, I don’t need childcare etc I have quite a bit of disposable income. Dp benefits from earning a lot as his living costs are minimal, I will pay more in for trips away etc. he has more disposable income than he would if he was with someone who earned less.
I absolutely wouldn’t, put my wage into a shared pot for us both to have equal access to.
I think it’s fair if, for example, a man earns a lot and wants his wife to be a sahp or only work part time so he doesn’t have to rush out of work to pick the kids up when they are sick, doesn’t want to drop offs, pick ups, works late all the time, doesn’t want to do their fair share of household tasks. These things men often claim have to happen to keep earning what they do. Though I don’t really believe it. I work in a male dominated industry and it’s amazing that plenty of women who are parents and are directors mange to leave on time, do drop offs, take responsibility at home…..but the men couldn’t possibly.
If a man is sucking out of home responsibilities, it’s usually a choice. And if that choice, is going to heavily impact the career and earning potential of the other partner I think shared finances is fair.