...in which case there would be no benefit from government for being married (such as tax breaks) and no harm from being unmarried. Don't ask the govt to get out of the marriage business unless you’re willing to give up tax breaks, inheritance laws, mandated health benefits, and all the rest that’s within the govt's purview (and maybe you're okay with that).
By the way, govt will never get completely out of marriage willingly, even at the local level - think they'll give up their paltry license fees? And giving benefits (like tax breaks or health benefits) gives politicians power. Good luck with taking that away.