So by your explanation, Lyle, the original John Waters 'Hairspray' movie is totally a musical? Because that's where I find the DVD when I go into HMV. And ALL of Stephen King's books are Horror, because they're in the Horror section? Even his Fantasy and General Fiction and Literary Criticism books?
Most shops won't differentiate between soundtracks and cast recordings because most of the world doesn't care, but when you get into the theatre world, you find the people who do care. And once you know the difference, it really starts to grate. I don't really care that the shops don't seem to know any better, it's not their bag. But as it's my bag, I like to be accurate, and I know a great deal of other theatre fans do too. Even if you yourself don't care and are happy being wrong, it'll save everyone else's heads - and probably decrease needless drama and debate - if you do us the courtesy of keeping the two terms separate.

And I've found non-Dress Circle shops that separate out soundtracks from cast recordings. In fact, I've noticed quite a few shops now simply call the section "Films & Shows", which helps my twitchy accuracy bone no end.