How so? The drug dealers are converting Tide back to dollars, and a significant portion of their business is still done with paper currency.
The drug user is who acquires the Tide, and then barters it for drugs. As other have pointed out, shoplifting Tide carries less risk than burglary, armed robbery, prostitution, etc.
If anything I think this speaks to the resourcefulness of drug users, and/or, the effectiveness of black markets.