There used to be buckets or drums full of sand at gates and outside buildings. You had to point your muzzle down towards it when clearing your weapon. One would often see the signs of bullet impacts in said sand.

Cleared weapons (generally with ammunition on the person) in a war zone stems from a rather simple calculation. More people would accidentally shoot themselves or others than are likely to be lost due to an enemy action. One of the Corpsman from here was recently shot in Afghanistan. The shooter was a Marine who had an accidental disharge in the bunker and shot the poor Corpsman in the leg while he was sleeping. (And Marines are arguably better trained with their weapons than non combat troops in the other services...)

This really isn't a new idea, at least not for the Army. The US Army tightened up regulations regarding going about armed circa 1942/43 as a result of problems with soldiers who were bored, esp when on leave, shooting up the rear areas and local cantinas. It was also during WW2 that careful officers and NCOs began making men tape down the safety spoons on their grenades owing to the number of accidents related to these.

Most general officers are armed, if nothing else, as a symbol of their rank. For a great many years, and perhaps still today, the USAF issued a special pistol for generals as did the Army. You can see one of the AF examples - a 9mm SW auto no less - on display in the NRA museum.

However, handguns are quite well distributed these days, probably seeing their widest issue since World War 1.