Perhaps because my AG is a bit unusual, the bonding makes more sense. It's a self-standing steel truss based structure--very heavy. Each long side is a 2.6' wide by 4" high truss 40' long--and weighs in at close to 900#. These, along with the buried cross braces are all bonded. A special clamp, made of brass or bronze (I think the later), attaches the wire to the member being grounded.