Why the sarc? It’s perfectly reasonable for a politician to quietly design a tax that will affect a group clamoring for an issue only if that group gets their issue.
Once the group gets what it wants, it is now beholden to the politicians who championed their cause. Those politicians want things in return. Sometimes the contstituents know what that thing is, sometimes they find out later.
I would assume that an actuarial or accountant would have informed the designers of the plan that the more married people the more tax revenue would be receive. If the base is enlarged, the system will be “better” funded.
That’s right, for a politician it’s almost always about the money.