Easy...my mirrors show a view right down the side of my truck looking
Backward...but nothing shows me a view looking forward of the side of my vehicle.
The mirror allows me a perfect view to be sure my truck isn't close to the car next to me, but if I pull in forward I have to try and remember just how far out the corner of my bumper sticks as I have no view of it without sticking my head 3 feet out the window.
The new 360 degree cameras make it much better. However the turning wheels being to the rear also make it much better (think of a forklift)