"Muso" and "Journo" Usage and Origin

Question

I have been watching a lot of British TV recently and I hear the word "journos" for journalists and "musos" for musicians, but I don't ever hear these words in the US. From my understanding they don't have to be plural, i.e. "muso" might also be used, but I am no expert obviously. Edit: I believe "pol" for politician is another. (Pol is apparently used in AmE also)

Are there any other shortened (collective?) nouns like these in British English? Any particular reason why this isn't done in the US English?

Edit after comments: This question is specifically about nouns that describe a group of people or a profession that are shortened. "Profs" might be one example that is used in AmE, though I don't hear it often, and it doesn't have the same -o ending.

Answer 1

According to John Ayto & John Simpson, The Oxford Dictionary of Modern Slang (1992), both journo and muso originated in Australia. Here the dictionary's entries for the two terms:

journo noun orig Austral A journalist, esp. a newspaper journalist. 1967—. TIMES Journos who work with the written word are seldom at ease with spoken English (1985). [Shortened from journalist + -o.]

...

muso noun orig Austral A musician, esp. a professional one. 1967–. K. GILBERT I used to be a muso and a hustler from the city but I'm a tribal man too (1977). [From musician + -o.]

Eric Partridge, A Dictionary of Slang and Unconventional English, eighth edition (1984) doesn't have an entry for muso, but it dates journo to circa 1940:

journo. A journalist: Aus.: since ca. 1940. (B.P) The almost ubiquitous Aus. -o, taken over—in part, at least—from Cockney immigrants.

Partridge's remark about the "almost ubiquitous Aus. -o" suffix corroborates curiousdannii's comment beneath the OP's question that "In AusE there are loads of diminutives like this."

A couple of booklets from the National Museum of Australia—Aussie English for Beginners (2002) and Aussie English or beginners Book Two (2003)—identify several other -o slang terms used in Australia: arvo (afternoon), bizzo (business), compo (worker's compensation payment), garbo (garbage collector), rego (motor vehicle registration), and smoko (smoking break). Both bizzo and garbo seem to meet the OP's specific request for "other shortened (collective?) [occupational] nouns like these."

Answer 2

The '-o' ending is very common in English usage, even when it doesn't necessarily shorten the word (yobbos instead of yobs, for example).

I can't be sure why this is, but for some reason I'm thinking it's something to do with the kind of slang used in upper class prep schools and public (by which they really mean private/exclusive/fee-paying) schools like Eton, where nicknames are an important indicator of social acceptance but often aren't meant to be insulting or demeaning (because the school is full of future industry leaders and politicians, it doesn't do to anger a classmate who might be in charge of you one day!). Because of this, they're often based on surnames - longer ones would be contracted but shorter ones are lengthened to give them two syllables, which sounds catchier. Keats, for example, becomes Keatsy or Keatso; Cameron becomes Camo and so on.

I know it seems tenuous and I'm sorry I can't think of the source for this or where I got it from! There would certainly be plenty of future 'journos' and 'musos' among the ranks at these schools, anyway...