[PeterisP]

The point is that a hundred million people could well do with not spending the time and effort to copy-paste that information and figure out if they're doing that correctly, and there also would be a hundred million less declarations for IRS to review.

That's how it works in quite many other countries; if you don't have anything peculiar, then you simply don't do anything at all, the appropriate taxes were already withheld by the employer and that's it. You file a declaration if you're running a business, are renting property as a landlord, or something like that, but the vast majority of "normal people" do not need to care how the tax declaration process works.