It's an order-of-magnitude estimation. Turbo Tax offers multiple products with different prices. Even if you plug in more exact numbers and use the cheapest product you get a hefty sum of 9 billion (150M individual returns * $60). IRS total budget is 11.5 billion and they do way more than just process returns.

There is no way an e-File system run by IRS would costs additional 9 billion dollars per year. They already do most of the calculation internally.