Taxes aren’t a negotiation... 90% of taxes are known because IRS has all of the data already.
The strategic goal of any tax organization is to maximize voluntary compliance and invest enforcement for maximum return. Pre-prepared returns would eliminate most of the fraud committed by normal people.
I wouldn't call myself "anti-tax," but I definitely prefer to pay lower taxes, and as few flavors of tax as possible, so maybe that meets the definition you had in mind. I dislike paying income tax in significant part thanks to the painful process we use in the US. And that painful process is principally due to the complexity of our tax law and the IRS treating all taxpayers as guilty of fraud by default, expecting each to prove otherwise.
Given the modern surveillance state, the IRS could send most of us a form saying, "We know you owe $X more than you had deducted; pay up, citizen." But they do not. In fact, for most of us, the IRS could more seamlessly handle our withholdings so that April 15 is a complete non-event, but they don't do that either. Basically, they don't provide services to taxpayers. We're not customers.