Uncle Sam should make all people turn in their cash for electronic currency on their account. Drug dealers, fences and other folks would have to declare their cash they have in boxes or lose it. Then, Uncle Sam could ask these people where the money came from and tax these people who don't pay taxes. I never saw a drug dealer or a fence take a check, somebody's plastic, etc. for product, only cash. When it comes to stolen property, guns are highly sought after. Guns are bought and paid for in the black market and are difficult to trace. Why? Cash. Even a guy who stole a gun and later sold it would have a paper trail. If a felon tries to buy a gun from a reputable source, his account would be flagged and frozen as well as the merchant's account.