> The IRS is the most bang for the buck government department. Every dollar spent there nets out many more, because they're chronically under-resourced to audit the whales who can trivially hide their tax obligations.
This is just a trope.
Auditing big whales is often not the most efficient use of resources because their taxes are a) much more complicated, and so more expensive to audit and b) more likely to have been done by a team of competent lawyers, so even though they're engaged in all kinds of shenanigans, the shenanigans are legal and there is no money to be had by auditing them.
Where the IRS can "turn a profit" is by auditing small and medium businesses, because they're more likely to have screwed up, and auditing them is cheap to the IRS. But this has a different problem. It isn't cheap to the taxpayer being audited; they pay an order of magnitude more to go through the audit than the IRS does. And then most of them are innocent, even though the IRS makes it back from the few that aren't. For obvious reasons the innocent ones hate this with the fire of a thousand suns, because nobody compensates them for their costs even though they did nothing wrong. But if you actually did compensate them for their costs then it wouldn't be net-positive for the IRS to do all those audits.