With automatic filing, the IRS will tell you how much you owe. And it becomes incumbent on you to prove them wrong. Under this model, taxes will calcify for poorer cohorts of filers who lack the means to contest a possibly unfair tax bill.
Personally I feel we need free filing. But I don't want the IRS doing my taxes for me each year and sending me the bill.
https://www.propublica.org/series/the-turbotax-trap
https://www.propublica.org/article/inside-turbotax-20-year-f...
https://www.propublica.org/article/turbotax-maker-intuit-wil...
https://www.ftc.gov/legal-library/browse/cases-proceedings/1...
But maybe the thinking is then the rich's tax loophole people's ploy would be too obvious?