Both in New Zealand and the UK (the places I’ve lived), many copper POTS lines were underground, same as fibre. Out of the urban area it actualy makes more sense to go over head for cost and repair.
For HV power lines I believe that heat retention is a major factor in underground, and there are plenty of ‘last mile’ that is underground - but that is not HV and a lot less load
Some one with better answers will come along and explain it better I’m sure
Both in New Zealand and the UK (the places I’ve lived), many copper POTS lines were underground, same as fibre. Out of the urban area it actualy makes more sense to go over head for cost and repair.
For HV power lines I believe that heat retention is a major factor in underground, and there are plenty of ‘last mile’ that is underground - but that is not HV and a lot less load
Some one with better answers will come along and explain it better I’m sure
Australia also has most of its telecommunications cabling underground