When inquiring after the immediate origin of a thing (i.e., where I purchased this gallon of milk), my wife will frequently say, "Where does it come from?". This always sounds odd to me—I'd say "Where did it come from?".
My impression is that the continuous "does" implies the coming from is somehow an essential part of the thing's essence—as opposed to an incidental fact about where I got it. After all, it doesn't sound weird to ask "Where does he come from?" in relation to a person's nationality. By extension, if I were to ask someone where a gallon of milk "comes from", I'd expect an answer like "Ohio dairy cows"—not "Kroger". But I can't articulate the grammatical terms much better than that.
Her construction isn't particularly wrong, is it? Just odd? She comes from an Amish Mennonite background, and I'm sure that's where this habit originates.
How would I grammatically describe what is going on when she says "Where does it come from?"