Not sure why the US isn’t able to do that. All employers and banks have your SSN, right? Sharing data with the IRS at the end of the tax year isn’t rocket science.
Basically, the Intuits, H.R. Blocks, Jackson-Hewetts, et al., stand to lose a large chunk of their revenues if the IRS did everyone's taxes for them.
Additionally, those in power, or with enough influence over those with power, do not want to fund the IRS to have easy visibility into all of those possible revenue streams in an easily correlated manner.
FWIW my effective tax rate last year was like 28%. To know down to the penny how much is going to taxes and not having to worry about filing would be a dream.