“I don’t think that I would want to be a cheerleader, telling those people that don’t want to pay their taxes: ‘Hey, you know what? We are not going to be able to come after you because I don’t have enough money,’ ” Mr. Kelly said, later adding, “Those comments are better kept internally.”

This see-no-evil approach to tax collection is especially frustrating, given the significant gap between federal spending and federal revenue. The government’s most recent estimate, which dates from 2010, is that Americans fail to pay more than $400 billion in taxes each year. That is enough money to reduce the annual federal deficit almost by half. It is more than enough money to maintain the current levels of funding for each and every government program that the Trump administration proposed to cut in its 2020 federal budget.

And there is every reason to think that the underpayment of taxes has increased since 2010, as enforcement has declined.

ProPublica reported last year that I.R.S. audits declined by 42 percent between 2010 and 2017. The I.R.S. has especially pulled back from scrutinizing people who do not file tax returns; new investigations of cases like Mr. Avenatti’s fell from 2.4 million in 2011 to just 362,000 in 2017.

The agency’s critics say it wastes money and uses personnel inefficiently. Probably I.R.S. employees, like many of us, could work a little harder and do a little more. But the sobering reality is that the number of I.R.S. auditors has been reduced by one-third since 2010. The government employs fewer people to chase deadbeats than at any time since the 1950s.