Nikon, at least, lets you set a variety of different autofocus policies with regard to what happens when you want to shoot at the precise moment when the image is out of focus. I've got mine set such that it always takes the picture immediately and autofocus is completely disconnected from the shoot button. Instead, I use the "AF-ON" button the back to pick my focus, then reframe the shot. (Exactly like I used to do with manual focus cameras and that goofy split-screen focusing gizmo.)