Oh no they’ve always collected it themselves, you just have to wade through ~4K pages of tax code that has averaged one change a day for the last decade.

But if you get it wrong, they’ll happily mail you a correction if you erred low. Plus penalties and interest of course.

The middle men like Intuit are a symptom of the legislature trying to use taxes to incentivize or disincentivize every little thing and still get pork for their districts. There’s a good 20 pages of code and case law on the depreciably of race horses that I’m sure the Senators from Kentucky had a hand in.