When Congress authorized $80 billion this year to beef up Internal Revenue Service enforcement and staffing, Republican House Minority Leader Kevin McCarthy invoked the language of war to warn that “Democrats’ new army of 87,000 IRS agents will be coming for you.” A video quickly went viral racking up millions of views, purporting to show a bunch of clumsy bureaucrats receiving firearms training, prompting alarm that the IRS would be engaged in military-style raids of ordinary taxpayers. The GOP claims were widely attacked as exaggerations – since the video, though from the IRS, didn’t show official agent training – but...