The US tax code isn't created to work like this. Direct file asked many questions about things like dependent children, whether you're blind and whether you have an HSA - all things that are relevant to your taxes that aren't actually available to the government right now.

Secondly, there is the issue of State / Local taxes - the IRS only receives federal tax data making it hard to automatically fill out the whole tax return since efiling products tend to file federal / state taxes together.

This year, direct file allowed people to import their W2s and 1099-INTs automatically based on the information the IRS had: https://github.com/IRS-Public/direct-file/blob/main/direct-f...