Not exactly by hand though - all the prep is done by hand but the actual alignment and fusion steps were automated by the fusion splicer machine (about the size of a small toolbox)

From a high level, the preforms are a lot more complicated, and I imagine the draw process might be more unforgiving (in terms of size fluctuations of the cross-section), but I don't see anything that is going to be prohibitive or that will make the fiber itself 10x more expensive in the long run. Most of the cost of an undersea cable isn't in the silica anyway...