Earlier quoted context omitted.
> the vast majority of people would accept this estimate. And the vast majority of people would then overpay. The IRS knows income, but they don’t know expenses.
This would be true if it weren't for the standard deduction. Something like 90% of all filers opt for the standard deduction, obviating the need for itemized expenses. Almost everyone would be best served by IRS calculated taxes. It's the wealthy and those with non-wage income who need the alphabet schedules.
This is a lot of people now, thanks to the gig economy. Similarly, farmers plus people who work for tips (at employers that do not centralize tips).