[kens]

Oh good, a non-geopolitical question :-) I think there are a few reasons why the shift registers aren't all next to each other. First, there are 6 shift registers (6 bits), but they interact with two 4-bit multiplexers. So you have blocks of three chips to position. Also, the top bit of the shift register is modified for the cursor, so additional chips are required for that shift register. So it's not as easy as putting the shift registers together, since there are other chips involved.

But why are they at opposite sides of the board? I think that is because the shift registers are very simple chips as far as connections, just 6 pins in use. So it is a lot easier to put them at the edges than a chip that has 16 pins in use, since there are only a few lines to route.

Note that the large vertical gap between rows of ICs so there is room for all the horizontal wiring. So I think the board had more capacity for horizontal wiring than vertical wiring. As a result, related circuitry is in the same row. E.g. the display stuff is in the same row (mostly), the CPU, peripheral adapter, and RAM are in the same row, and so forth. I think the video circuitry is in the top row so they can put the output connector at the back.

I'm sure there are more constraints on routing this board that I can only guess at. Even from a quick look, there seem to be a lot of factors.