[runako]

> The government is naturally incentivized to maximize revenue

This is a fundamental misunderstanding of the situation. The tax law is what it Congress decides it is. The law depends on taxpayers to report their incomes as well as deductions and other facets of their financial lives (e.g. household size, addresses, etc.).

A government-run tax prep site couldn't necessarily pull in all of your deductions, that's correct. But it also couldn't necessarily pull in all your income (especially business income, offshore income, etc.). It's mostly neutral in that respect.

[missedthecue]

But most Americans have at least a few deductions. How many Americans have offshore income? Especially the ones that would be relying on gov. tax prep?

In this case, it is mostly one sided

[runako]

See: https://news.ycombinator.com/item?id=32513370

Roughly 90% of Americans file using the standard deduction ($13k for a single person, $26k for a married couple filing jointly). Median household income is ~$67k, so the median household is not itemizing.

The remaining 10% of people would not be bound to use the free public system.

[missedthecue]

You can qualify for a number of deductions without itemizing.

[runako]

Correct, but in that case there is no impact to your taxes.