It should be noted that burying lines in this case is not for aesthetic reasons, but because trees falling on/growing into above-ground lines is one of the most common causes of wildfires. Putting the lines below the ground is much safer in that respect, but it is much harder to do maintenance on the lines should something go wrong.

Most of these lines are likely in regions where almost nobody lives, but a fire started in those forests can threaten a much larger swathe of customers.