Why abandon the thread just as the facts are being given? Look at some of the quotes from that article.
Before Donald J. Trump became president and after, his exceedingly complex and voluminous tax returns came under regular scrutiny by the Internal Revenue Service. The number of agents assigned to the audit team: one.
After he left office, the I.R.S. said it was beefing up the audit team, to three. The tax agency itself acknowledged that it was still overwhelmed by the complexity of Mr. Trump’s finances and the resistance mounted by the former president and his sophisticated army of accountants and lawyers, which included a former I.R.S. chief counsel and raised questions early last year about why even three revenue agents should be assigned to audit him…
“This return has about 400 flow-through returns reported on Schedule E and, since some of these are tiered, report a total of about 500 flow-through returns,” the auditor said.
Underscoring the need for more resources, the memo went on to say that to “do a thorough review of these returns, we would need a team much larger than the current team.”
It’s not simply Trump, of course.
[T] he committee reports released this week highlight how depleted the I.R.S. has become in the last decade, as Republicans starved it of funding. They also show how the agency has become increasingly unable to crack down on wealthy taxpayers who push the legal limits to lower their tax bills and have the means to fend off audits if they get caught. [bolding added]
Note that this is not an opinion piece; it’s a front-page news article. Why is the IRS allowing the rich to amass $7 trillion in unpaid taxes? Republicans.
Republicans have for years accused the I.R.S. of political bias and unfairly targeting conservatives. For that reason, they have fought to cut the agency’s funding or, in some cases, called to abolish it altogether. …
Can we do something? We have, but the Republicans are going to crush it.
The Treasury Department, which oversees the I.R.S., is planning to use some of those [Inflation Reduction Act] funds to hire more auditors who can tackle complicated tax returns. …
[Ted Cruz said] “I think we ought to fight an epic, knock-down, drag-out fight over stopping the Democrats from funding 87,000 new I.R.S. agents to harass and intimidate and persecute Americans and their political enemies.”
This is the answer to the OP. Republicans have been systemically gaming the system for decades. (I’m sure some Democrats have colluded, but nowhere near the same extent.) The IRS could work. It could hire more people to do audits. It could even hire more people to answer phones for ordinary people without tax accountants, which is where most of those new IRS agents are supposed to go. But Republicans don’t want any of that. It makes for a better enemy who is secretly working for their side.