Keeping taxes hard to pay is an important carrot in keeping the public mad about having to pay them in the first place. It's governance through dark patterns.
I am pretty sure the reason most people are mad about having to pay taxes is the thousands/tens of thousands/hundreds of thousands of dollars of their income that is taken from them.
On the high level, I always felt fortunate that I was in position to have to pay a lot of taxes. But it's pretty ridiculous. Case in point, we just bought a small, 100 year old house on a tiny lot. New York State didn't hesitate charging us a "mansion tax" on it. Believe me, it's no mansion. While there's a limit to how mad I am about that, it's not the paperwork that's annoying me.
Put another way, we are at the lowest tax rate this country has seen in a century. How much lower can we expect it to drop?
Perhaps this depends. In the USA, perhaps. In Iceland, not so much (https://twitter.com/iamharaldur/status/1355490017288867841).
In the USA you have to pay your taxes and then you have to pay for your public insurances, where in most of Europe these are the same things. And perhaps tax payers in the USA are not happy with this. So to amend your statement, perhaps a more accurate one is: Most people are mad about paying taxes because of the thousands of dollars of income that is taken from them without any tangible benefits.
US is vastly larger. New York City alone has 3X as many public school students as Iceland has people. We are vastly diverse ethnically, culturally and geographically. It is much harder to find "problems and solutions everyone agrees to" in the US than in Iceland.
I’m sure you’ll find way more happiness towards paying taxes in the UK and China then in the USA despite being as diverse and even larger then the USA.
Taxation exists in every functional modern democracy and there are no viable alternatives to it. States and municipalities that reduce their revenues through tax cuts wind up relying on things like speeding citations and civil forfeiture to bridge the gap. Wouldn't you rather suck it up and pay once per year than potentially having assets seized by a random cop that you then have to go through the legal system in order to get back? You're gonna pay either way. Even in anti-tax states like Texas, people get hit with massive property tax bills because it's one of the only ways that the government generates revenue.
The real problem is that the vast majority of people don't really care once the money leaves their hands. You don't like the mansion tax, which makes sense, but have you taken the time to look at your state or city budget to see where all of this money is disappearing to? Because that's where the more of the focus needs to be. Just glancing at the executive summary of the latest NY budget(0), it looks like $86B of the $212B total goes towards Medicaid alone.
So do we just leave the poor to not have healthcare? Why does healthcare cost so much and how come despite all of these tech entrants into the healthcare space, the cost never seems to go down? I really hope for the sake of your own argument that you don't work in healthcare, because what that industry is doing to communities across the nation in terms of cost is nothing short of outrageous.
[0] https://www.osc.state.ny.us/reports/budget/review-enacted-bu...