The US doesn't have a nationwide grid because of the technical requirement to use AC back when electrification happened (which requires phase matching or DC intertie between subregions), and because of the politics of who regulates the grid (which is why Texas still has its own grid.)

The AC requirement is a legacy historical issue; a nationwide DC grid could be built in the US tomorrow if the political issues could be solved (and if it made economic sense to rip out the legacy AC infrastructure, which it doesn't.)

> Having a global grid is a futuristic pipe dream.

It's more like a series of tubes.

If we condition on people taking the energy transition seriously the past might not be a good predictor of the future. But whether there will be a strong pull towards "optimality" might depend on what is the total cost of sub-optimal alternatives. I would think that a well distributed grid would also minimize (beside losses) also storage costs and would also have various other redundancy benefits...

Not a pipe dream because it is futuristic, but because it is geopolitical.