Earlier quoted context omitted.
Literally all of that information is already being reported to the IRS by the relevant companies on forms 1098, 1099-whatever, W-2, W-4 and whatever other schedules apply. The IRS defines the rules, they built an engine to take all that into account to ensure you're not lying on your taxes. They just have to literally run it and send you the printout for verification with a remittance stub. The rest is regulatory cap…
Literally all of that information is already being reported to the IRS by the relevant companies on forms 1098, 1099-whatever, W-2, W-4 and whatever other schedules apply. But not instantly. And not all of it in time for April 15th. Sometimes those details don't make it to the IRS for years. We don't yet live in a world of instantaneous information transfer about every American citizen to the government. Some people…
Tax filing and payment periods can be amended to accomodate that, even the fiscal year. It is not like these periods are unchangeable articles of basic law.
FYI we get all those figures ready by the start of March here in Turkey (Turkish yearly income tax deadline is March 20th). US can clearly figure a way out with three times as more people than Turkey.