As someone with 15+ years experience in building powerlines,...

As someone with 15+ years experience in building powerlines, that doesn't make sense.

The costs of power are roughly (very rough) 50% generation, 50% transmission.

The cost of generation is independent of the length of powerline (they don't care).

The cost of a powerline (with everything) is the initial cost of construction and then ongoing maintenance (like most things). If it is any good, maintenance costs are very small for a single line (comparatively speaking). Annual budget for maintenance for a 100km line (33kV) would be significantly less than $100k (there's obviously a ton of factors to consider to get an accurate figure).

There's nothing in your statement to substantiate why power costs would be significantly different to a customer close to generation or one further away?