Ok, I disagree with the TurboTax reasoning, but I think your argument doesn't make sense... if most people have their pre-filled tax forms making them pay more than they should, then everyone is going to compute their taxes themselves anyway to avoid paying too much... at that point, why is it better than the current system?

(Edited to correct an error)

About 20% of people (particularly low income people) have simple tax returns and file using 1040EZ. If the IRS computed that form, then what they send out would be ideal for the majority of taxpayers. So it would benefit those by eliminating the expense of tax preparation without actually costing them more in taxes.

Then there are those like myself who fall into an in-between area. I have more complex taxes, although not as complex as a lot of people, but would gladly pay more than is strictly necessary in order to not have to bother with figuring them out. In fact, I already do, in the form of paying a tax preparer (I fully consider the expense of tax preparation as a tax itself.)

Those whose taxes are more complex are very likely aware of that fact, and would continue to do their own tax preparation.

Also, if the IRS provided a prefilled 1040EZ, that would make computing your own taxes easier because you could use the figures supplied as a reference.

1040EZ died after tax year 2017: https://www.irs.gov/forms-pubs/about-form-1040-ez

To nuance this - they've been refactoring/shuffling the forms around.

  2017 Form 1040EZ goes up to box no. 14
  2017 Form 1040 goes up to box no. 79

  2018 Form 1040 has no boxes for $ amounts!
  2018 Form 1040 Schedules 1-3 is where they all went, if you needed them.

  2019 Form 1040 added boxes back up to 11b
  2019 Form 1040 Schedules 1-3 also exist

Basically, Form 1040 is now "EZ" by default. For those with more complicated tax filings, you've had your work scattered to the four winds - I mean, three schedules.