Dodging taxes is as old as taxes themselves. Just ask Mr. Trump, who has employed systematic dodging for decades, according to a Times investigation.

We got a good look at one of the bigger problems, the proclivity of the wealthy to hide cash from the I.R.S., in 2008, when the Justice Department was able to pierce the Swiss bank secrecy veil during an investigation of UBS. The department uncovered thousands of rich Americans who were hiding about $18 billion in offshore accounts arranged by that Swiss bank. Many were compelled to fess up and pay up. But eight years later, the Panama Papers, millions of files hacked from a Panamanian law firm that specialized in caching money for the rich and powerful, disclosed that there were still plenty of rich people willing to play hide-and-seek with the I.R.S.

The odds are in their favor, and growing. ProPublica reported that I.R.S. audits dropped 42 percent from 2010 to 2017, a period in which the I.R.S. budget was lopped by $2.5 billion, adjusted for inflation. New investigations of people who don’t file dropped to 362,000 last year, from 2.4 million in 2011. That costs the Treasury $3 billion annually in uncollected taxes. More than $8 billion in back taxes did not get collected in 2017 because the agency couldn’t get to them before the 10-year statute of limitations ran out, another worsening problem. Tax delinquents can simply wait the agency out. ProPublica estimated the total shortfall of uncollected funds since 2011 at $95 billion .

These uncollected billions could pay for any number of things: better care of wounded veterans, infrastructure improvements such as a desperately needed new tunnel between New York and New Jersey. You could even build an expensive wall.

One area where the I.R.S. still bares its teeth is in auditing people in the lowest tax bracket. If you are claiming the earned-income tax credit, which provides cash for people who typically earn less than $20,000 annually, you are as likely to be audited as someone earning between $500,000 and $1 million. ProPublica reported that 36 percent of all I.R.S. audits focused on this group. It may not be a crime to be poor in the G.O.P.’s America, but you can expect to be treated like a criminal for accepting the government’s cash to make ends meet. At best, that’s an inefficient use of I.R.S. agents: Compliance should apply to all, but the I.R.S. should do most of its fishing where the big fish are.