It's more fundamental than this. Money (as in easily exchangeable, verifiable and divisible tokens of exchange -definition excludes raw precious metal) doesn't exist without taxation. Taxation can exist without money (see the Roman tax code under Diocletian, or various peace treaties where payment is promised in raw gold) but there is no instance in all of history where money exists without taxation. Money is never just a means to settle private debt. It is always there to settle public debt as well. People settle on one medium of exchange (a coin, for instance) out of an infinite realm of possibilities (shells, pearls, purple cloth squares) because that one medium is the medium that the government collects taxes in.

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