> transmission lines are already pretty efficient and we already choose less efficient materials for cost
You're correct, and this highlights a problem I often see in discussions: "efficiency" just is a measure of benefit/cost. Without knowing the units of benefit and cost, people aren't making meaningful statements when they say "efficient". The important efficiency of transmission lines is capacity per dollar, not capacity per material, and no material requiring lab crystallization is going to be remotely competitive in capacity per dollar.
You're correct, and this highlights a problem I often see in discussions: "efficiency" just is a measure of benefit/cost. Without knowing the units of benefit and cost, people aren't making meaningful statements when they say "efficient". The important efficiency of transmission lines is capacity per dollar, not capacity per material, and no material requiring lab crystallization is going to be remotely competitive in capacity per dollar.