[posterchild]

Such ambiguity is a nuisance as well. It’s similar to when people use local terms, abbreviations, or initials and expect everybody has their local knowledge.
OC - Osceola County? Occupied California?, Ontario Canada?
Tri State Area - which 3 states?

[Joe 6-pack]

I think there are two things in play with such ambiguity: laziness and self-centeredness. Being precise takes a little more effort. People may think they are streamlining things on their end and making a process more efficient, when in fact, they're muddying the waters and jamming up the works on the other end. I have multiple clients, some of whom will use the same acronym or abbreviation as others, with entirely different meanings. Fortunately, I'm pretty good at reading them in context.