Here is an individual scrapper that got nailed in 2013 by the IRS:
USDOJ: US Attorney's Office - District of North Dakota
"Omerovic, a self-employed scrap metal dealer, in 2006 purchased and obtained scrap metal in Fargo and the surrounding area, which he then sold to a number of scrap metal dealers, primarily in North Dakota and Minnesota. The investigation conducted by the Internal Revenue Service - Criminal Investigation Division, showed that Omerovic’s gross receipts for the year totaled in excess of $152,000, with an estimated tax loss, for sentencing purposes, of more than $30,000."