This is why I qualified with "general-audience" -- I have no doubt that different industries/companies etc worked out vocabularies to optimize costs, or even that there were some common shared codes. But did the vestigal telegraph codes you saw look anything like the stuff in this book? I might well be completely wrong -- I have no dependable intuition about the period at all -- but I somehow can't shake the impression that this is mimicry rather than the real thing. Sort of like mongodb successfully convinced countless naïfs that it was some sort of google bigtable style technology that would simplify their lives, handle their scaling and save them lots of money (whereas in reality it was vastly inferior to existing free RDBMs offerings in all metrics save marketing and ease of (unauthenticated) installation).
The fact that common ones were listed in general audience documents like day planners and dictionaries should tell you it was important. You can even see commonplace examples pop up in old novels and even movies from time to time — if you don’t know, they can sound like weird slang, which of course is what they are.
Also pretty general purpose: sure, I imagine some companies had special codes, but as they would sell these books at stationary stores they were the kind of thing you’d need to go buy if you list yours or left it at home, say as a traveling salesman. After all, reducing “six units of model “luxury natural” need replenishment” to “AVOCADO SIX REPLENTISH STOP” saves you 5/8ths of an expensive charge probably coming out of your commission.
A hundred years ago a stamp cost a penny, a newspaper or cigar five cents and a five word telegram could cost a dollar (with Western Union that included physical delivery to an address, though you had to tip the boy).
Commercial code books like this were quite common and available in office supply shops apparently into the 1960s at least. The point of these code systems was not to keep a secret but to significantly reduce the cost of sending telegrams which charged by the word (and were handled by humans so you couldn’t save money by omittingspacesbetweenwords — the clerk taking your order would just put a stroke between the words and would declare the charge.
I originally learned this because, back when we had paper appointment books, they also often included appendices with handy info: time zones, common abbreviations, etc and when I was a kid, vestigial telegraph codes. Dictionaries often had sections with stuff like that to, and these were quite important in translation dictionaries.
Into the 70s phone trunks were quite limited and you often had to reserve a long distance phone line ahead of time, so telex/telegraph survived quite late. I was sending email and casually logging into remote machines over the net in the late 1970s yet to book a plane ticket in the 1980s could still require sending a telex.