The key distinction you're circling is this: showering affects nobody but you. Marriage and childbirth create **claims against other people** — inheritance, property, custody, next-of-kin decisions, citizenship, child support. Paperwork isn't there so the man and woman know they're together. They already know. It's so that the hospital, the bank, the court, the school, and eventually the child can know, without having to take anyone's word for it.
**Nobody invented it in one go.** It accumulated:
- Parish registers of baptisms, marriages and burials spread across Europe from the 1500s (England ordered them in 1538, the Catholic Church in 1563) — largely to settle inheritance fights and prevent bigamy.
- England's Marriage Act of 1753 outlawed informal "clandestine" marriages, because secret unions were being used to defraud heiresses.
- Revolutionary France moved registration from church to state in 1792; England set up a civil register in 1837, partly for public health statistics.
- ID cards and passports as we know them are mostly a 20th-century product of war, conscription, and the welfare state — once a government promises pensions and schooling, it needs to know who qualifies.
**The real function is a substitute for community memory.** In a village of 200, everyone knows whose baby that is and who is married to whom. In a city of 10 million, no one does. Documents are what trust looks like when it has to scale between strangers.
**The advantages fall mostly on the weaker party.** A woman with no proof of marriage historically had no claim on property when the man left or died. A child with no birth certificate is close to invisible — hard to enroll in school, prove their age against child marriage or child labour, inherit, or get a passport. UNICEF estimates around one in four children under five worldwide are unregistered. That is not a small problem.
**The other side is real too.** Registration makes people *legible* to the state, and legible populations are easier to tax, conscript, police, and sometimes persecute — census records have been used for exactly that. It lets the state define which unions count. And it turns something intimate into an administrative object.
But notice the irony in the couples you're describing: in many countries they haven't escaped the law at all — de facto or common-law status attaches anyway, and they still register the birth. What they've usually gained is easier exit; what they've often lost is protection if one partner dies or the relationship ends badly. Some want that trade deliberately. Others just haven't read the fine print.
**Will it go away?** Almost certainly not — but it's changing shape. Paper is dying; digital identity (India's Aadhaar, the EU's digital wallets) is replacing it, which means *more* registration, not less, and more continuous. Marriage specifically is being unbundled — civil partnerships, cohabitation agreements, private contracts covering property and children à la carte instead of one package deal.
So: less ceremony, more data. The direction is away from *one* document that means everything, toward many smaller ones that each mean something specific.