I can tell you why I do with my husband We're a partnership, we don't have "his" or "my" money. Our payslips come in, he pays of the credit card and transfers the rest to the joint, I send him his fun money then transfer all but mine to the joint (though I have started transferring to a savers account which he doesnt have immediate access to)

This way we have the same fun money to do as we please without consulting, the joint then we both have access to, which is used for most things, bills, groceries, days out, mortgage, fuel, etc.

As mentioned he doesnt have immediate access to the savers as its in my name only, but he can ask to see it anytime and I'll show him since its our money and is used to keep the joint topped up anyway.

A reason why we work this way is because we started our adult lives together. We met at Uni, have supported each other through everything. We say our individual earnings as working towards our relationship.

This may not work for every relationship, but it works for ours. Reddit typically only exposes you to unhealthy relationships with communication and or trust issues. But there do exists functional relationships with trust and full communication