> Why do we need any of this? Physics takes care of it if we just hook everyone up to a grid.

That's exactly what is the bottleneck: the grid. Operating a grid, eating transmission losses etc. cost a lot of capital and labor. Not to mention: its also a single point of failure. Whereas communication (through cellphone towers) is cheap(er).

> It’s kind of like saying why don’t we pump and sell well water to one another instead of using a common water supply where the runoff from all our land goes to the same pipes.

Its not the same, and I don't think its a good comparison. Solar energy is much more plentiful than groundwater, and does not require any "processing".