If someone is openly selling pot on his front lawn, and conducts his business in such fashion as to be bothersome to his neighbors, he should be prosecuted if the neighbors complain. Likewise if someone is intoxicated and disorderly in public and others complain about that.
A person being disorderly in public hinders public movement and posses a danger.. A person selling pot on his front lawn hinders no ones movement or a danger to persons passing by. I suppose it may bother a neighbor in the same way that nude sun bathing bothers a neighbor or a driveway-mechanic doing business from his house in a residential neighborhood. Those I think are zoning laws violated. A local government jurisdiction, not state or federal.
I didn't mean to imply I thought the guy selling on his lawn should be a federal offense, but rather focus on the principle that laws should be enforced on the basis of complaints. The police's job shouldn't be to try to find places where the law is being violated except to the extent necessary to enforce other laws (e.g. the police may try to track down a fencing ring on the basis that its operations represent a continuation of already reported crimes).
BTW, one of the IMHO good things about the fact that drug laws used to be a 'revenue' issue is that their enforcement was left to "rev'nooers", who may have been despised but whose function could reasonably be seen as unpopular but necessary. Today, however, the drug laws are enforced by agents who cannot reasonably be said to be trying to collect legimate tax revenue (they may be trying to enhance revenue by stealing people's stuff but that's hardly the same thing). That rev'nooers were despised did not rub off on the rest of the police. But when the general police start acting as rev'nooers, that's no longer the case.
"And where else will this degenerate son of science [Hume], this traitor to his fellow men, find the origin of just powers, if not in the majority of the society? Will it be in the minority? Or in an individual of that minority?" --Thomas Jefferson to John Cartwright, 1824.