I did not realize it was the super high voltage lines. I would think they would be placed in areas with wide, extensive and cleared rights of way. Oh well!!
You are correct - that is where they are placed.......but still, they cross highways, rivers, and much more where burying them would bankrupt every utility.
The other thing is look and you will see that the high big transmission towers are sometime in multiples of 3 or 4, some carrying paired (double) lines in parallel.
I know a place near an interstate not far from us that has 3 high towers, 2 with dual lines, and a 3rd with dual-dual - or 4 lines per phase.
That would mean burying 18 - separate super high-voltage lines in each right-of-way (ROW). ONe cannot imagine the cost.....or time......many years of construction - perhaps a decade......