So the IRS should document (for public consumption) the exact algorithm it uses to decide which filings get extra scrutiny? Doesn't that open the door to quite a bit of abuse? (i.e. tax fraudsters being able to match just the precise set of conditions to not be audited).
Yes, the IRS should. The fraudsters (and rich people with expensive accountants) already have this info, for example by hiring former IRS examiners and executives. Making the algorithms public at least puts everyone on equal footing.