The vast majority of money laundering cases both in size, quantity, and every other dimension are predominantly cash based.
Drug Traficking Organizations (DTOs), engaged in the trafficking of a variety of drugs into the United States, use numerous methods to launder proceeds, which remain predominantly cash based.
While $2 Billion is not a small amount, this is news because it involves Bitcoin.
Compare that to this: $200 Billion in fines to U.S. banks...Money laundering by banks is not an anomaly. It's a business model.