Trust me, the edges are plenty sharp, but the pieces are small and are therefore unlikely to cause large cuts. Also, when they shatter, they don't leave shards in the windows to cut you if you needed to climb out, or if a rescuer was trying to get in.
That about covers it. The glass will shatter into many tiny pieces so that it sctters on impact instead of acting like window glass where it tears into shards that can cause very serious lacerations. The small glass pebbles are still pretty damn sharp and will cut you easily, but they are so small that they wont make very deep lacerations. It will go everywhere upon impact and very little of the glass typically stays intact in the channel of the window. The stuff thats left over in the track can easily be wiped out with a gloved hand and cleared so you can get in or out of the car pretty quickly in an emergency.