No inventor sat down at a blank slate and said "Hey, let's string 700KV power lines across the country on huge towers". Overhead powerlines developed gradually

No inventor sat down at a blank slate and said "Hey, let's string 700KV power lines across the country on huge towers". Overhead powerlines developed gradually from an overhead line running power from one side of someone's lab to the other, to power running between buildings, to city wide distribution and beyond. As time went on, the powerlines got larger and higher voltage. There aren't a lot of options -- underground powerlines are possible, but they have their own disadvantages so are not a clear-cut winner.