[vel0city]

The federal government doesn't always know if you've had a child or if you've died. Not even specifically the IRS, but its possible for you to have a child and never involve any organization that reports to the federal government.

[fragmede]

It is absolutely possible, just as there are tons of other exceptions that Direct File wouldn't cover. The point is that there's a golden happy path that many people trot along where things could just be easy.