Why can't we have marriage laws written that well, where both sides agree to how it's written
and can still get out of it the interpretation that matches their beliefs.
Because, for most people, the point of government is to force their values on others.
Not for most people, no, but for a minority of frightened reactionary conservatives, yes.
Unfortunately, in some states and jurisdictions, that frightened, reactionary minority manifests as a majority which advocates denying citizens of the United States their rights and protected liberties motivated by unwarranted fear and hate.
That’s why we have a Constitution and its case law, to protect the rights and protected liberties of citizens from abuse by state and local governments.
Such is the ridiculous hypocrisy of conservatives and libertarians: they rail against the perceived ‘abuse’ and ‘overreach’ of the Federal government, yet when state governments engage in the same abuse and overreach, conservatives and libertarians are suddenly blind to that abuse and overreach.