Whether they are packed by hand or machine, a pre-roll cone smokes better when it's packed evenly and finished symmetrically. Experienced consumers know that cones should be evenly and densely packed, filled with a coarse grind for proper air flow, and twisted at the top for a balanced light. At the industrial level, automated pre-roll machines must be as gentle as the human hand and even more accurate.
When an individual packs their own cone, they are subject to their own human error. But when a consumer buys a pre-roll at a dispensary, they expect it to burn evenly, smoke smoothly, and taste just like the strain they purchased.