The government needs money to spend. Fiat money comes from nothing. The government that controls the fiat money can produce it in any way.

Taxes are a money sink, not a money source. Taking money collected as taxes to turn around and spend it is a traditional way of operating, but it only was necessary before because money used to be hard currency. Now money is not hard currency, and taxes-for-revenue are there because of inertia, not necessity.

Eliminating taxes is not a viable option, but that has nothing to do with the need for revenue. Taxes force commerce to happen in a particular currency, taxes sink money to control inflation, and an effective tax regime projects governmental authority. These are all important and serve as valid justifications to maintain taxation. Then, as I said already, the form and amount of taxes also controls behavior through nudging.

Viewing taxes as a source of revenue is correct in an accounting sense, but the government does not operate on the principles of accounting. Accountancy of a sovereign government's finances in the age of fiat money is just record-keeping; the government controls the ledgers, not the other way around.