Blame it all on BDA (Bomb Damage Assessment). This is the business of figuring out what to bomb, and what the impact on the enemy is after you bomb. The problem, of the guys in the air getting fooled by the guys on the ground, began during World War II. Right after that conflict, the U.S. did a thorough survey, of the impact of strategic bombing on Germany and Japan. It was discovered that the impact was far different from what BDA during the war had indicated. The air force fellow vowed to do better next time. But as experience in Korea (1950-3), Vietnam (1965-72), Kuwait (1991) and Kosovo (1999), Iraq (2003) and Lebanon (2006) demonstrated, the enemy on the ground continued to have an edge when it came to deceiving the most energetic BDA efforts. The only proven technique for beating the BDA problem was to have people on the ground, up close, checking up on targets. The Israelis did not want to do this, because of the risk of some of their commandos getting killed or captured, and because the intel and air force people were sure that they knew what Hizbollah was up to down there.
What happens now? The U.S. Air Force has demonstrated, over half a century, an inability to solve the bad BDA problem. Will the Israelis be any better? We'll just have to wait and see.
In southern Lebanon, Israeli troops are frantically trying make up for some major mistakes by Israeli air force and intelligence units. Despite the best efforts of Israeli intelligence, and clear knowledge of what was going on, Hizbollah's efforts to secretly build bunkers in southern Lebanon were largely successful. The Israelis knew Hizbollah was fortifying the areas along the Israeli border, which Israel abandoned in 2000 ( in an effort to bring peace to the area). Israel knew something was going on, and depended largely on aerial reconnaissance (jets, UAVs and some spy satellites) to identify what Hizbollah was doing. Based on this intelligence, the Israelis worked out plans for how their troops would deal with Hizbollah if war came. War did come last July, and it was quickly discovered that Israeli intel had missed many of the bunker complexes. These were then discovered, with some difficulty, by Israeli ground troops.