Larry Summers explains it:
https://www.washingtonpost.com/opinions/2023/01/16/republicans-house-irs-tax-service/
Paywalled, so here's a couple clips:
In past work, we have shown that an investment in the IRS similar in size to that of the Inflation Reduction Act would generate more than $1 trillion in additional tax revenue over a decade by reducing the “tax gap” — the difference between owed and paid taxes. But this is, in fact, conservative, as recent research has emphasized a point left out of our calculation: Successful audit activity raises future collections from taxpayers who face enforcement activity. If their home office deduction is disallowed once, taxpayers do not attempt the same deduction again.
Reasonable people can disagree about how progressive the tax code should be. But we cannot see any logical argument rules that operate differently for certain taxpayers. Most Americans have most of their tax liability automatically withheld and earn income in ways that are reported directly to the IRS — for example, interest income on the 1099-INT or dividend income on the 1099-DIV. But the most privileged Americans accrue income in opaque ways that are not subject to this type of reporting and, therefore, are a source of a large percentage of the tax gap.
The whole thing is worth reading. Summers is no fool, and no puppet of any administration or agenda - he did manage to get himself fired as Dean at Harvard for saying some unwoke things. He's not offering a spirited defense of our system of taxation; he's just stating the simple fact that if this is our system, it ought to work fairly across persons from all income categories and ways of generating income. Right now, it doesn't.