[jjav]

> They don't have all the data.

For nearly all people, they do.

They do know your investment earnings (brokerages report that) and your mortgage interest (loan companies report that) and your kids.

That covers, just about everyone.

Sure, a few people have personal businesses and rent incomes and all kinds of complex things. So the rational thing to do is build an automated system that covers the needs of 99+% of people, and for the few ones that it doesn't work, let them opt out and do a traditional tax return filing.