Palestine is a relatively lawless place, where weapons are common. Still, there's enough gang mentality that the guys you see shooting off those weapons are probably hooked up with one gang or another.
Iraq, in my opinion, is a different story. It is, much more heavily contolled, especially in the central region of the country. The government is very strong--witness the omnipresent tales of fear and torture. I bet those with weapons have some "loyalty" connection to the Baath party. I don't think its the city Kurds in the North, for example, or the marsh Arabs, who are armed enough to act as a balance on Saddam's government.