Haha... this is damn dumb, but I was thinking our eyes have excellent focusing and VR technology. Our focusing is quicker than AFS, and performs well in very low light. Its even quieter than AFS too. And then, there is the VR technology. Try this.... lock focus onto something, move your head up and down vigourously..... the image doesnt shake at all, super VR, compensates for more than 10 stops of light.
But then my eyes seem to have some back/front focusing problems.... need to wear a filter in front to correct.
Although our AFS is damn good... sometimes, the focusing can get loss sometimes. Every got groggy looking at a metal cable at close range... it fools the eyes, and your eyes just cant focus. Just now I was lying in bed, checking out how long it takes for it to focus from the edge of my pillow to the wall.... and the ... suddenly.... it got confuse and refuses to focus on the wall, needed to half press shutter again and again... haha. Need to go technician liao.