Rich folks only need so many mansions, yachts and designer sweat pants. This would further shift the burden of taxes onto lower income folks who spend 100% of what they earn.

The IRS could just present a form behind a login with an itemized fully calculated tax return with an accept? "yes" / "no". They already have all the information they need, and already do the work when checking returns for errors.

Taxes are a pain because both, corporate capture of government by powerful tax preparation companies and also because a certain political ideology wants paying taxes to be as unpleasant as possible to make the concept of taxes as unpopular as possible.