Bear with me here: is it possible that people in different places have different words for things? Spoiler: it is just as accurate to call it a "pop machine" - in fact, more accurate here, because if you told your kid to visit the soda fountain they wouldn't know what the hell you were talking about. They would probably imagine an actual fountain, but of coke or something.
It's almost like language evolves.
Me: "Nobody here uses the term "fountain" in that way and would be confused."
You: "Well, they're just WRONG."