In all of the pictures/discussions of power transmission equipment, I have noticed that there are four conductors:
Three are "phase" conductors, and one is a "neutral" conductor.

Fast-forward from the power generation, "high-tension" lines, etc. to the wooden poles at the curb here.

There is one primary conductor entering the can, and three secondary conductors exiting--two "legs" of a 120/240 service and the neutral.

The other day, I happened upon a POCO employee and was chatting with him.

He explained to me that the line at the top is a 4kv line, and that no neutral is used on the pole because the can is grounded. Each pole has its own ground rod.

My question is, why do some distribution systems use a neutral wire and the ones here do not?

I asked him if the "messenger" cable was the neutral for the 4kv, he said it's not, it's just that, a messenger cable. If that's the case, is the messenger cable energized also? Are 4kv lines even insulated?

Just wondering.