Most money is created by the private sector. Thats was fractional reserve banking is, creating money.
But it is true that when a bank creates a loan (which to them is an asset, but to the borrower is a liability - debt) it creates a matching deposit (a liability to them) which does increase the money supply. The amount of central bank reserves is not hugely relevant to the process, that's more of a liquidity management thing. The main limitation is actually capital adequacy regulations.
But all of that aside, a Government doesn't need banks to create money so they can tax it, it permits banks to do it by granting them a banking license.