> it's functionally impossible to build new overhead transmission lines anywhere
This isn't really true, new overhead lines are being built all over the place. It definitely depends where they're being built and there is definitely strong opposition from councils in e.g. some parts of Germany, but see for example in the Netherlands there are definitely new overhead lines being built: https://www.tennet.eu/nl/projecten/provincies/groningen/eems...
That being said it's true that it's much more challenging than it used to be to get planning permission.
This isn't really true, new overhead lines are being built all over the place. It definitely depends where they're being built and there is definitely strong opposition from councils in e.g. some parts of Germany, but see for example in the Netherlands there are definitely new overhead lines being built: https://www.tennet.eu/nl/projecten/provincies/groningen/eems...
That being said it's true that it's much more challenging than it used to be to get planning permission.