Although SlamTex's interpretation of this section is incorrect, I believe it has more "common sense" merit than the actual Code. I see a big difference between an underground feeder with an Equip Grd and an aerial Triplex to an outbuilding.
A 30' length of #8 copper has a lower resistance than the homeowner's knee to concrete connection. In the case of a hot to box short, it will cause the OCPD to trip.
Lightning in this area (OC, CA) is a rarety.
For us to run a 700'+ feeder in a warehouse building is not at all uncommon.
Why then, is the Grounding Electrode required, even though the buildings might be only 1' apart, on the separate structure?
(As a side thought, would I be called if the ground rods were 2' apart from each other?? curious) [Linked Image]