So it's time to file taxes in the United States and it occurred to me that I am required to provide a lot of information that the government already knows. For instance, I have to provide the contents of my W-2 form, but my employer already sent the Internal Revenue Service a copy of that document. Indeed, if I don't accurately report my income, the IRS will know because it differs from the information that they already have.

Why doesn't the IRS just save me the trouble of submitting information it already has and just send me a "bill" telling me what I owe (based on the information it already has)?

Obviously, there is some information I would still need to fill out, like self-employment income. But wouldn't it be easier, and save more money for everyone, to just have the IRS tell me the information it knows and, if I don't have any corrections or additional information that I need to report, just ask me to write a check and send it back?

EDIT: I'm interested in the political rationale for the IRS not doing this. As some commenters have noted, countries in Europe already have a system very similar to this where the IRS-equivalent discloses their known information and the individual fills in unknown information (such as self-employment income), so I am aware that it is technically feasible.