I mean maybe it's partly TurboTax, but I think it's also the fact it's made by lawmakers and not engineers. I mean there are forms that are literally circular references: "your AGI is the sum of these numbers, but if one of the numbers in the sum is negative, it can only be negative if your AGI minus that entry is less than some amount."
No, its 100% turbotax and similar groups like H&R block that benefit from people having to do their own taxes that are to blame here. Your gripe of stuff being stupid and complicated for no reason is also their fault to some degree. See, it turns out that the harder and more annoying filing taxes is and the easier it is to mess up the more money people use turbotax/tax prep people.
A simple way to look at America is that if something is wrong and a small group of rich people/companies benefit from it and all it does is annoy/minorly upset everyone else in the country then it isn't a bug, its a feature of American Capitalism.
As someone who works as an actual tax preparer for a tax preparation company, heretofore and forevermore unnamed, I'd like to just chime in to say you're mostly right. Things are made difficult on purpose and, to put my tin hat on, taxes aren't taught in public schools specifically to squeeze money out of ignorant people, and to obfuscate the inner workings of the system so it is legitimately difficult to tell how the system works. If you can't tell how the system even works, how can you fight against it?
I will partially defend my own job however, and say that the taxation system is a somewhat good pressure valve to relieve the strain on poor folks, as people making little money generally are getting the lion's share of the available refundable credits, and if you made less than 12,950 of taxable income, then you don't even have to file taxes. Though it might still be a good idea to collect your withholdings, the EIC, the CTC, the AOTC, and any credits particular to your state. There's more obscure credits you can be entitled to, but those are for obscure situations.
Also, while the IRS does get a copy of all the income you've earned... that's through money that was correctly reported from an employer on a W-2. The IRS cannot tell how much you've earned while self-employed, aka Under-the table. You're supposed to report all income, no matter the source, and the IRS is not omniscient. Of course, you can just elect to not report that income and hope the government never notices... which is easy for small sums, but anything bigger than that, then good luck. The Tax Man is Watching.
Also, the IRS cannot tell if your life situation has changed, and having a professional to walk you through the tax process and correctly assess your life situation is important because people's lives and family situations have a habit of becoming stupidly fucking complicated. For an easy example: suppose a boyfriend and girlfriend live together all year with their child, which they just had that year. The IRS is not keeping track of who's having babies, or where those babies are living, or who's taking care of them, and it's up to the couple here to decide who gets the Head of Household Filing status, the Child Tax Credit, the Dependent Care Credit (if applicable), and the Earned Income Credit. These are significant, and the laws surrounding them are pretty strict in order to avoid fraudulent claims.
I'm still a first year tax pro, but I can see how the system kinda works.