[dTal]

To control the money supply. It's true that the government don't need to directly fund all spending with taxes, but if more money is issued than collected, the amount of money in circulation increases and the currency devalues. Obviously this should be avoided as the more the currency you're printing is worth, the better off you are.

So practically speaking, you do have to fund expenditures with taxes. You can't just create value out of thin air.