Comment by FranOntanaya

That was often a "mechanical" issue with analog captions. You could send only 4 bytes of caption content with each frame (and some were control codes) and the display only fit 32 characters per line. If several people were talking over each other, talking rapidly, or there were on screen texts that needed captioning too, they'd make compromises to try and fit everything.

Then, because of legacy broadcasts and backwards compatibility, that carried over well into the 2010s.