The trolleys do remove the distasteful experience for the JWs of having a door slammed in their face or other negative interaction with a worldly though. This really leaves the onus up to the 'heathen' to come get the life saving message, removing the responsibility from the JWs for actively trying to save lives.
I suspect when results of very few to no publications being placed by these apathy carts/trolleys makes its way to Beth-Hell, some 'nu lite' or other instructions from the GB will be forthcoming.