Because marriage is a financial contract. It doesn't seem reasonable to use the argument that you can't punish people financially because innocents are involved in the consequences, as that fails in other venues. If a company is involved in an environmental violation most of the stock holders are oblivious but we fine the company, not the executives.
I just find its complicated that someone can be denied a treatment they need because they can't afford to pay for it even though they are owed the money to cover it, because someone was legally allowed to operate a motor vehicle without insurance and did so in a manner causing serious harm.