The thing that is blocking that happening is intense lobbying by intuit (and a few others) plus anti-tax groups. See https://www.propublica.org/article/how-the-maker-of-turbotax... for what was probably that best quick summary from about 10 years ago.
Do you have any reason to believe that?
Are they your documents? Can you accrue taxes independently?
just from my personal experiences... either way, the IRS has that info, if they assume people are honest... not sure why it isn't public.
There are 36 countries that manage to do return-free taxes. They seem to have a base rate that covers most (~64% in the UK) people. The US tax code is way more complicated than one base rate for everyone. It's unclear to me how anything other than income tax is handled in these countries. Does the UK have a capital gains tax? Tax deductions?
Edit: I looked it up.
Yes, the UK has capital gains taxes and they must be calculated by the taxpayer.
https://www.gov.uk/capital-gains-tax/reporting-and-paying-ca...
There are also deductions for savings and dividends. Those deductions look a lot like the US deductions. They also (sometimes?) have to be calculated by the taxpayer.
Saving interest is often paid gross but if you go over the savings allowance and don't fill in a tax return HMRC will just automatically take more tax from your payslip.
There is also a £20,000/year ISA allowance which shields investment from tax so any holdings within an ISA can be ignored for tax purposes.
However, the dividend and CGT allowances have been reduced recently as the government tries to find ways to raise more revenue without raising the headline tax rates, and the £20k ISA allowance hasn't been raised for years despite inflation.
So as it stands, in the future a lot more people will have to start filling in tax returns.
Interest and capital gains come in sooner for Americans. Plus we have way more deductions. I can deduct business use of a home office and personal vehicle. That’s not something the IRS can know.
They just won't do it before you do. That way, they might learn things they didn't yet know, from people who decide (as legally obligated) to divulge additional information. I assume that they assume that far fewer people would divulge additional information, if their "you talk first, I talk second" tactic went away.