I agree, the issue here is how one interprets 'structure'.
In the past, we've had discussions where some would argue that a pole that only carries the meter and a disconnect was not a 'structure', thus not requiring its own grounding electrode system. Others would point out that a pole with a meter on it is something built, and therefore a 'structure'.
I'd like to take a somewhat different path of argument: the house is clearly a structure, and the pole/blocking/support for the outside disconnect is also a structure...but the cabling between the two is also something constructed, and thus ties these two items together into a single structure. As a single structure, you have no requirement for an additional main disconnect
-Jon