It's not quite that simple. There's a lot of popular political support for things that make a simpler tax season impossible, too.
For example, the existence of tax-advantaged savings vehicles such as IRAs and HSAs mean that the taxable portion of your income isn't settled until the deadline for making contributions for that tax year. Which is April 15. But I imagine there would be a lot of popular political backlash if Congress were to abolish IRAs in the name of sticking it to Intuit.
There's also that whole mess of expenditures that you can deduct from your taxable income, which doesn't kick in until the total of your deductible expenses exceeds the standard deduction. And a lot of people were worried when the standard deduction got increased a few years ago. It made a lot of people's taxes nominally easier to calculate, but people were worried that it might remove an incentive for charitable donations, or reduce the largess that the government gives to homeowners relative to renters, or alter the impact of tax incentives for people who put solar panels on their roofs, or whatever.
Long story short, we love to blame Intuit, and it is true that Intuit generally wants a nasty complicated tax code, but it's also true that, in the aggregate, so does America.
Yes, but for things where all you have is a W-2, the IRS could easily do your taxes for you. They could send everyone a letter saying, “based on what we have, these are your numbers. If you want to change what we know, feel free to file yourself or with something like TurboTax.” Then you get the best of both worlds: people with simple taxes don’t have to deal with it, and people with complex situations can keep doing what they’re doing.
The (previous) existence of the 1040EZ showed that a lot of people have simple returns that the IRS could do for them.
This is making mountains out of mole hills though: these types of problems can be solved without abolishing tax-deductible accounts.
For example, one could tweak the deadline for contributions to those accounts to be say March 1, make the financial institutions report to the IRS by March 15th, send everyone their estimate on April 1st and have a deadline of April 15th to confirm or adjust their tax filing.
Most of the big things that involve deductions are already tied to a financial institution that already report to the IRS.
It's not like Turbo Tax is the only thing standing between you and not having to do your own taxes. The entire system top down would need to be redesigned and the withholdings concept done away with. That'd be such a sweeping piece of legislation it will most assuredly never happen.