There is a limit to the amount of power that can be pushed through the cable on each end, and each strand of fiber needs a number of Erbium-doped fiber amplifie

There is a limit to the amount of power that can be pushed through the cable on each end, and each strand of fiber needs a number of Erbium-doped fiber amplifiers, which consume a lot of power. This isn't a problem on land, as you can add power at each regen site.