I think you’re seriously underestimating the amount of data the IRS would have to proactively collect. “We get your tax obligation right 80% of the time!” isn’t an acceptable SLA. Kids are born, houses (and electric cars!) are bought and sold, community college classes are enrolled in, …
Re: Primary residence: Uhh, OK, so I report to my state tax authority who reports to the Feds. I thought the point of this thread was that somebody else would do all this for me, but for the evils of Grover Norquist and Intuit?