Forensic accounting in action

The IRS will no longer target a wide-range of Coinbase users via its information request, which it filed on Coinbase back in March. Instead, the agency made concessions to seek account data of individuals who transacted — meaning they bought, sold, sent, or received — $20,000 worth of bitcoin in any transaction type. 

They continue to look at the public chains and omit those that follow through legitimately.  Then of the remainder look at those transaction whose values mostly coherent with the tax dodge flow.  Government got good shoe leather.