No it doesn't. It just changes form. See money laundering and the mob.

Can't collect in cash? That's a-ok. Do me a favor and you get your kid back.

You are not talking a lick of sense. Crime finds a way. It always will. You can't tax law abiding people to invalidate criminal economic models. All you do us disadvantage the victims, undermine the legitimacy of your legal edifice by implicitly raising it above those it serves in importance, and completely do away with any semblance of sanity, and maximize tge cost in human lives exacted from the pool of the falsely accused and victimized. Game theory doesn't apply. Rational Actor Theory doesn't apply. Addressing crime via draconian laws doesn't work if you're at all interested in any State even nominally centered around the concepts of Freedom and Liberty.

And a Ransom tax? Do you want tax collectors tarred and feathered? Or are you just trying to ensure that any remaining credibility in the government is irrevocably lost? Taxes lend legitimacy to things. You're basically admitting that a ransom is even a valid transaction by enshrining it in your tax code.

Absolute madness.