Only reasoning that my old mind can come to is being the metal weather head is outdoors and too high for a person to come in contact with risk of an electrical shock is very low. Never came across a weather head that was energised. Was scary cutting out some old 30 amp services high off the ground that had cracked rubber insulation. Would cut both wires close to utility splice but some times old rusted 1/2" conduit was higher then utility point of attachment. Not a big fan of plastic weather heads. The day before I would do a 100 or 200 amp service liked to make up the weather head with 3' of wire hanging out and two layers of white tape on the grounded conductor and silicone the top hood on so it could not fall off. I would start maybe an inch below where the wires left SE jacket so cable clamp tightened down on a few layers of tape.
That is my thoughts for this as well as a metallic head on PVC raceway.
Other sections of NEC basically don't allow the open conductors that leave the weather head to be at levels that are easily reached to begin with so the weatherhead is always above certain level anyway.
Lighting on wood poles that is maintained by POCO's almost never has grounding conductors. But also is up and away from people and IMO is not really a hazard. Many don't have any overcurrent protection either. Yet if I were installing them technically NEC still would require an EGC and overcurrent protection. I'll admit to installing many on farms over the years and connecting to overhead distribution with no EGC or overcurrent protection. Was doing that way before even giving much thought to whether they needed EGC or OCP. If we made a drop to a switch on the pole or even a switch in a building controlling the light then there at least was going to be OCP involved.
