I tried to pick a photo that showed clearly the set up in Qld. This happens to be the end of the wire at an overhead coal loadout, but will give you the general idea.
The steel overhead structure, and all the masts off into the distance, are not electrified, as they are directly mounted to the ground. But note the insulators, 2 vertical and 2 at an angle, supporting the end of the overhead wiring. Everything that is supported by these insulators is live. (Note the wire at the top of the masts on the left is not live, its an earth return, hence no insulators)
Now, note in this pic, the insulators on the supports of the overhead wires. Because they are insulated from the masts, the supports are also live, along with the wires. Note also, most of the wires at the tops of the masts are also insulated, they are live as well.
If a bird lands on the wire or supports, and stretches its wings enough to contact the mast, BOOM, fried bird. If it doesnt come into contact with the mast, then there is no problem.
Thats an issue with kids climbing masts, they dont realise the supporting structure is live. If they climb the mast, and reach out past the insulator to grab the angled support, then they are not happy chappies, unfortunately. Thats what the signs are for, I just wish people would read and understand them.