The US system is more complex, but I wouldn't attribute this to malice.
The reason why it's so easy to file taxes in lots of European countries is because the tax system (for the general population) is a lot simpler. For example in Austria you pay the same amount of taxes no matter if you're single or married, capital gains are taxed at a flat rate and directly withheld by brokers, and "social benefits" are typically handled outside of the tax system instead of being folded into the tax system.
In the United States the tax code is a lot more complex. You pay different taxes if you're married compared to if you're single, capital gains tax rate depends on your other taxes so brokers can't automatically withhold taxes, and there are a lot of edge-cases for certain other situations that can't be easily automated. Like tax credits if you're affected by natural disasters, different tax handling for railroad worker pensions, and so on.
With that complexity it is a lot harder to automate taxes, but it's also hard to retroactively reduce that complexity, as any changes will negatively financially impact some of the affected groups. Also I think that it might be easier in the US to handle those aspects as part of the tax system (instead of handling them independently), as the federal government has the authority to collect taxes, but direct payments (outside of the tax system) to individual groups might be harder? (But I'm not sure if that's true).
But all of that complexity seems to be added with good intentions. Just look at the "Coronavirus Tax Relief" as the latest example which by itself has a long FAQ page describing all of the details: https://www.irs.gov/newsroom/coronavirus-related-relief-for-.... Adding that to the tax code was probably the best short-term approach to quickly ship something (and lots of people are probably in favor of those changes), but that complexity adds up over time.
To me this looks somewhat like the broken windows fallacy: In countries where the tax code is simple and allow for "automated" taxes nobody is going to advocate for a new law if it makes filing taxes a lot more complicated. But in countries where the tax code is already complex adding one more complex law doesn't make too much of a difference.
Some of the complexity is also due to the design of our governments. I don’t know much about taxes in Spain, but I’d guess the number of income tax jurisdictions there is not a 3 digit number.
I file in both the US and Spain. There is nothing particularly more complicated about the US. Some aspects are more complicated in Spain (both countries tax on worldwide income). The notion that the complexity of the filing explains the inability to do it online is complete nonsense.
My post does give the tone of malice, and certainly what I was thinking about while writing but not my intention. But I do recognize there are "good reasons" why it should be manipulated as well.
I think that efforts to suppress things like "Easy Tax" where the feds would send you a pre-filled-out form that you could agree or disagree with are almost certainly malice. There have been multiple attempts over the years and the anti-tax Norquist crowd comes down. If they can't end taxes, they don't mind it being difficult to file taxes and they say that it's because they wouldn't mind someone accidentally under paying or under reporting taxable income and it not getting caught.
Part of the political resonance with the tax issue is the cost of doing taxes and the stress it causes. If the process was as simple as verifying a document, signing it and sending it back (or heaven forbid, docusigning it and clicking 'next') then the discussion changes to "what are my taxes doing?" and "is this worth it?"
I really like your second paragraph, hadn't considered that.
I have a hard time seeing past malice, when some of the most high profile easy to target tax dodgers consistently pull it off with only good outcomes, or when the IRS is given more money to specifically target them yet doesn't.
The reason why it's so easy to file taxes in lots of European countries is because the tax system (for the general population) is a lot simpler. For example in Austria you pay the same amount of taxes no matter if you're single or married, capital gains are taxed at a flat rate and directly withheld by brokers, and "social benefits" are typically handled outside of the tax system instead of being folded into the tax system.
In the United States the tax code is a lot more complex. You pay different taxes if you're married compared to if you're single, capital gains tax rate depends on your other taxes so brokers can't automatically withhold taxes, and there are a lot of edge-cases for certain other situations that can't be easily automated. Like tax credits if you're affected by natural disasters, different tax handling for railroad worker pensions, and so on.
With that complexity it is a lot harder to automate taxes, but it's also hard to retroactively reduce that complexity, as any changes will negatively financially impact some of the affected groups. Also I think that it might be easier in the US to handle those aspects as part of the tax system (instead of handling them independently), as the federal government has the authority to collect taxes, but direct payments (outside of the tax system) to individual groups might be harder? (But I'm not sure if that's true).