Touching the door handle to lock/unlock will only work if the key fob is within range, so there must be a radio signal present?
I always use the touch method to lock the car, as I'm stood right next to it I can see and hear it is locked, plus I always have the door mirror auto-fold on so I can see when I look back, the car has been locked. When in a public space I also double touch (touch, wait a couple of seconds and touch again) the handle to deadlock the car. This means even if a window is broken the car doors cannot be opened from the inside.