The pole is a structure.
This is the whole point of using the term structure.
250.32 Two or More Buildings or Structures Supplied from a Common Service.
The NEC could have named this section simply "Two or More Buildings Supplied from a Common Service."
They did not, they add the words "or Structures" this is to make clear that this does not only apply to "buildings" but anything built or constructed.
As a result of the broad definition of structure, exceptions had to be put in place for light poles. Light poles are structures and as such would be required to have a disconnect switch located on each pole.
These exceptions to 225.32 demonstrate that something as simple as a pole is a structure.
Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be located elsewhere on the premises.
Exception No. 4: For poles or similar structures used only for support of signs installed in accordance with Article 600, the disconnecting means shall be permitted to be located elsewhere on the premises.
One thing I think worth stressing is this part of 250.32(B)(2)
there are no continuous metallic paths bonded to the grounding system in both buildings or structures involved,
You must be careful to think of all possible metallic paths, not just the raceway the conductors are in.
Water and gas pipes, phone and cable TV wires, it is possible even a metal fence might run between two metal structures creating a parallel path for neutral current.