Financial independence.
Anyone who thinks SAH parents can free themselves of this worry is naive. You never get the time back, you never get the experience back, you never get the training or the raises or the bonuses. You never get the retirement savings. If you are unfortunate enough to live in the US you are entirely dependent on your spouse for healthcare.
It's an unfathomably vulnerable situation to be in but it gets brushed off. There is still an attitude that SAH is a 'gift' given to a parent, see how often a working spouse will say they 'let' their partner stay at home, that the working partner 'supports' the family. A SAH spouse is not an equal partner with a 50% contribution. More of an oldest child with extra responsibilities and a higher allowance.
Pre-nups are often advocated as a way to ensure fairness if the relationship falls apart. I'd rather see pre-SAH legal documents. The SAH spouse gets half the earnings, gets half the purchases, gets half the retirement savings. A working spouse who isn't willing to sign it is a working spouse who doesn't believe that being home and watching children is a 'real' job.
