What's the sense in painting a yellow line on the top of the fence if it has no significance?
Purple, green, polka dots -- it doesn't matter what color it's painted.
If the ball clears a fence, whether it's chainlink gray or monster green, it's a home run. If it hits the top of the wall and goes over, it's gone. If it hits the top and bounces back, it's not.
In driveway ball, if it goes in the air over a parked car across the street, it's a double. Over the lowest wire between the telephone poles is a triple. Over the highest wire is four bags -- every time.