I didn't shoot across the road, I didn't shoot across my neighbor's fences, I shot directly into the air.
The downward force of gravity is a major factor in the spread of shotgun shot. Not all shot will be of the same velocity, and slower shot will drop faster. If you shoot straight up, then the slower shot will still drop, or slow, but it will still be on line.
So, if the shot was straight up, and the drone was hovering, the shot would have been much easier, even at a distance, with a shotgun vs a rifle.