I think they meant that there was a time when people’s jobs were: 1. either reading notes in shorthand, or reading something from a sheet that was already full

I think they meant that there was a time when people’s jobs were: 1. either reading notes in shorthand, or reading something from a sheet that was already fully typed using a typewriter, or listening to recorded or live dictation 2. then typing that content out into a typewriter. People were essentially human copying machines.