Paying estimated quarterly taxes four times a year wasn’t bad. I calculated my withholdings, remitted my tax payment through EFTPS, and was never surprised at tax time. I don’t think I ever got a refund or owed when I was doing it myself.
I learned that many people who have never contracted before are shocked they have to do this, lost on how it works, and had (then) no good place to go for actionable advice. I found that surprising and kind of sad in a way. We could be doing so much better with financial literacy.
But, get a raise, take a pay cut, find a new job, start or stop a second job, or a third, or fourth, get paid hourly, get sick, take time off to care for a sick family member, have a kid, go back to school, graduate, get married, get divorced, get a mortgage, pay down your mortgage, ... There are all sorts of scenarios that could change your tax situation on both the federal and state level, making it difficult to calculate how much you would owe up front.
What it really boils down to is our tax codes suck, and too many rich folk are keen on keeping it that way.
Setting aside the 90% thing, to your original point, paying taxes is not a voluntary thing. There is, however, at least some flexibility in how you pay them.
The flip side of this is: who cares, withholding is actually fine. For a vast majority of people, estimated withholdings is pretty close, and the few percentage points one might earn on a $1k refund in the meantime just isn't worth it.
In my opinion, the best easy tax situation would be that at the end of the year we can skip (most of) the filing step and I either get a check or a bill.