The above combined with the to me foreign notion that tax filings could be considered private(in Sweden, everyone's income and their complete tax filings are public information) probably makes it problematic for them to just send it out willy nilly. What if they sent you the wrong filings?
Based on a very widespread stereotype about Americans, I imagine the irs would get sued.
But, as previously stated, I've only been in America long enough to switch planes, so my guess is likely to be inaccurate!
On the digital ID part, the government + regulated industries like banking will enforce validating specific types of IDs via third party companies and data sources to use said government / regulated industry services - which is used as a hacked duct tape and silly string version of digital ID. Other than that… yep you got it.