It is very easy to pay nothing for tax filing in the US. There are multiple genuinely free e-file providers and most people could easily file their taxes themselves on paper.

That said, while I agree the IRS situation can be dramatically improved - move the Free Fillable Forms program to the irs.gov domain instead of just linking to it, for starters, or just buy out one of the extant free programs and incorporate it - takes like this miss a lot of important factors.

1. US taxpayers are filing federal and state taxes. The state tax revenue agencies are completely independent of the IRS. While free federal filing would be nice, you've only solved no-more-than 50% of my problem. (Many people have to file in multiple states.)

2. This is relatively well known, but the US tax code is generally more complicated than many other countries. This isn't so much of a problem except that US taxpayers are obsessed with making sure the government doesn't get one over on them. They are always on the lookout for deductions and credits, frequently that they may not even be actually eligible for. I personally know a lot of people who have illegitimately claimed commuting mileage on their taxes, for example. So the complexity is a desired feature, not something you can just remove without consequence.

3. Because of the US federal system and US privacy rights, most countries collect much more information about their citizens than the US federal government. The IRS and the US federal government do not even know where you live until you tell it; unlike many countries, there is no such thing as registering with the government when you move. They don't know what, if any, children you actually have living with you - which at $2000 tax credit per kid, is extremely important information when calculating your tax bill. Remember that even a national ID program was/is extremely controversial in the US. So to have automatic tax prep that's even close to correct entails collecting reams of information the government does not currently have. You could maybe make a start by re-using information from last year, sure...but that's going to be inaccurate in a lot of cases which will then cause it's own problems - people incorrectly not applying for credits they should have and you don't know to correct them, and people realizing they can probably get one over on the IRS.

4. This is an issue that mostly affects educated upper-middle class people, not lower income people. I have struggled to convince most lower income people to use free! tax prep software at all. Most of them are paying companies and individuals to do their taxes, convinced that some guy with an office has the power to arm-wrestle the IRS and get them more back on their tax refund than anyone else via secret loopholes that don't exist on the 1040EZ. (They are wrong, except to the degree the less circumspect filers definitely commit lots of tax fraud.) You will never, ever convince these people to use the IRS website to file their taxes - that's walking into the enemy camp, in their minds. On top of this, they are convinced that making a tiny mistake on their taxes will result in severe fines and penalties and possibly imprisonment, despite the fact the IRS generally is very amenable to working with you. (Mostly. One guy I know was forced to pay his taxes twice because the IRS refused to accept the payment they had on record as payment, because whoever processed it did so wrongly somehow.)