Fun fact about codabar, it is among the only barcode symbologies that can be implemented completely as a plain font.
And do you know if that was a conscious design choice?
Codabar was can be implemented as a font because the standard does not define specific start and stops symbols, instead it was developed as just a raw 1-to-1 encoding of character to pattern. It does not have check digits because it uses more space per symbol to handle error correction by making it very difficult to misread each pattern. The spacing (kerning) between each symbol is a different width ratio than the white bars found in each symbol.
Going back to dot matrix, it does appear that some early printers just had a grid of character “cells” in which the spacing between each cell was slightly more than a single “dot”, this probably explains the codabar quirk with 3 different space ratios (black bar, white bar, and inter-character quiet-space) and probably is the beginning of some further investigation into that topic.