People who are word-savvy enough to notice these missing apostrophes are likely to assume they're errors. After all, they know that possessives take apostrophes. Those are the teachers' cars. Visit the farmers' booths. That is the taxpayers' responsibility.
But in fact, those missing apostrophes aren't missing at all. Their absence is not an error. Yes, an apostrophe is required to show possession, but sometimes a term like teachers or homeowners or farmers or taxpayers is intended more as an adjective than as a possessor.
"Do not add an apostrophe to a word ending in S when it is used primarily in a descriptive sense: citizens band radio, a Cincinnati Reds infielder, a teachers college, a Teamsters request, a writers guide," instructs the Associated Press Stylebook.
It's a subtle distinction that leaves a lot of room for disagreement. One writer might think that a farmers market is all about the farmers, while another writer might feel that the market itself is the farmers'. Neither is right or wrong. But style guides like AP do contain a few specific rules.
For example, AP singles out teachers college as a term that does not take an apostrophe. But it doesn't give instructions on what to do when the word that follows "teachers" is something different, like "union" or "lounge." That's why, in AP style, some would write "a teachers' lounge in a teachers college," while others would write "a teachers lounge in a teachers college."
