Who Decides When a Hyphen Dies?

It was fun to read Stephen Wilbers's business writing column from today's Star Tribune. He tackled the question of compound phrase and words: when to use a hyphen or not, and when to use a space or not.

Over time, adjectival usages tend to go from hyphenated to a single word. Sometimes it happens with nouns, too -- he gives the example of weekend (which went from week end to week-end). Though, he notes, "Curiously...certain compounds such as high school resist evolution. Go figure."

Other examples are still in transition, such as health care -- which Mayo Clinic, for instance, has transmuted into healthcare. This appears to be a common practice in health industry writing (when they're talking to each other).

In my work, I frequently encounter the question of when to make a compound into a single word. In writing or designing for an industry or trade audience, there are many usages that begin to make sense as a single word. A couple I've come across:

• Foodservice -- the industry that makes food for large numbers of people, whether in an institutional setting or in grocery store prepared foods.
• Fairtrade -- the movement to pay producers, usually in developing countries, a fair price for their goods and work with them to build their businesses and economic power.
• Layout -- part of what a designer does. This becomes two words when used as a verb, but as a noun or adjective, it's one word.
• Startup -- whether talking about new tech companies or new food co-ops, I lost patience with hyphenating this one.
• Proofreading -- funny, I know, but I never feel quite confident about this one. Maybe it's that fread combination that looks like a strange word.

Wilbers discusses log on/in and set up and decides that they're all comparable to my usage of layout -- two words as verbs but one word as adjectives (and nouns, if appropriate). Why do login and setup sound wrong to me as verbs, when proofread doesn't?

It's a mystery how or when it becomes acceptable to make a formerly hyphenated word into a single compound word. My guess is it starts with writers addressing specialized audiences, then moves to the more general rules once it's recognized by dictionaries and style guides.

Who decided that nationwide and worldwide were one word, but city-wide wasn't, for instance? Is there a committee meeting in an obscure room of the New York Public Library?