The sellers drop the packages off in mailing boxes, ideally far from where they actually live. This would render your idea less worthwhile. There have been arr

The sellers drop the packages off in mailing boxes, ideally far from where they actually live. This would render your idea less worthwhile. There have been arrest of sellers and buyers, primarily due to noobish mistakes. All told, the risk for the seller is much lower than dealing with a variety of forces in the street in their local jurisdiction. Therefore your idea becomes a war of attrition for law enforcement. Where the yield is too low to justify the cost. This is why more effort goes into shutting down the marketplaces, but even this has become a war of attrition ever since the Silk Road 1.0 bust. The federal government operating through just one agency got 80 million in bitcoin from that bust. The next year, the FBI required cooperation with 16 agencies across Europe in a dragnet bust that only got 1.2 million in bitcoin, with most sites being back online in a week. The trend continues, and every enforcement action simply prompts consumers, merchants, and site providers to implement UX and security practices that they already knew they should have been using (multisig addresses instead of human escrow, use of tails/whonix, not logging in as admin from a public library, etc)