If we just printed dollars to pay for all gov expenses, we would probably have a lot of inflation. Inflation hits all holders of dollars equally (on a percentage basis). Taxes allow us to spread the burden of shared costs (like infrastructure) in a different way.
Additionally, taxes act as a feedback mechanism on behavior. We can incentivize some things by giving tax credits for doing them, and we can disincentivize other things by charging higher taxes on them.
Balancing these two effects of taxes: inflation and policy, is hard. If the gov. wants to encourage everyone to buy an electric vehicle, we could give a big tax incentive to do so, but that reduces overall taxes, which means more inflation. To combat this, we have to print fewer new dollars or increase taxes somewhere else.
This is one of the big challenges for the Federal Reserve, they don't get to pick how much tax is collected, just how many new dollars are printed. If congress doesn't collect enough tax, there's only so much the Fed can do to balance things.