During the Vietnam War, David Hambling explains (in Swarm Troopers), the average distance by which a bomb missed its aim point, known as “circular error probable,” was about four hundred feet for bombing from medium altitude:
Four hundred feet may sound haphazard, but computing bombsights had improved greatly since WWII, when the average miss distance was three thousand feet.
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The real difficulty comes when attacking something like a bridge, where the target area of a roadway or support beam is just a few feet across. An entire Alpha Strike’s twenty-four planes may not be enough to score one solid hit.
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The success of laser-guided weapons at Thanh Hoa was the start of a revolution in “precision guided munitions.”
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According to a popular analysis of this improved accuracy, one modern laser-guided bomb was as effective against a point target as thirty Vietnam-era F-4 Phantoms dropping their entire load of bombs.
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(Using WWII technology, it would take the bombs from an incredible fifteen hundred B-17 Flying Fortresses to hit the same target.)
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Smart bombs though are not truly smart. All they do is go exactly where they are told. Unlike small drones, they cannot send back information about the target and get a close-up view. Weaponized drones are smarter than smart bombs.
The three thousand feet sounds highly suspect. A formation of WW2 Forts would drop all its bombs simultaneously on a signal from the lead bombardier. As the formation was spread out across the sky, side- as well as long-ways, and the bombs were released over a period of a few seconds (during which time the formation had traveled a thousand feet) the intention was to bomb an area, not a pickle-barrel pinpoint. In addition, Europe being Europe, the target might often be obscured by cloud, in which case the lead bombardier dropped by dead reckoning from the last definite fix. Before the night bombers started bombing on target indicators, the Riff-Raff were instructed that if the target was not visible they must bring their bombs back.