If taxes don't fund the government, why do we need taxes?

We can't solely print money instead of tax because it is the tax itself that gives the money value to print in the first place. The greater the tax, the more can be printed, the lower the tax, the less can be printed.

This is not because taxation removes money from the system (reducing supply and increasing value) - it is because the intial seed of value that allows fiat curerncies to exist in the first place is the demand generated from the force-enforced requirement to pay tax in that currency. Everything else is layers above. Without the tax, the system would have nothing to stand on.

Taxes don't fund 100% of the government. That doesn't mean that taxes can fund 0% of the government and everything will still work.