I agree that the font width, height, and spacing appears to require customization.
What was the technology used in 1966-1968 to produce the typography on the graphics in TOS?
Was it a stenciling system of some sort?
If we could understand that technology, perhaps it would elucidate the reasons for the unique spacing, heights, and widths?
Maybe the graphics guys were having to adjust for Standard Definition TV and were spacing letters out more in order to help with legibility?