Charles,
I think you are correct. That one has an intent to externalize a vision and one does it to one's satisfaction, that intent has been expressed in something physical and that is then satisfying. What's special about art, as I see it is that it gets a life of its own, even if it's not beautiful or has no purpose except to exist.
What separates the toilet form the Duchamp art is that one is valued as art and the other only when it's function is needed.
Think about a stack of 100 urinals in everyone's back yard. No one would buy any you offered for sale, as there would be no market. One that was connected to plumbing would allow one to have relief. That would be valued. Otherwise to see the worth of this design, we'd need to go to a museum showing such a urinal that Duchamp signed and that, depsite the stock of urinals everyone owned, would be still be priceless.
So while the object is the same, it's the special relationship to an artist that makes it worthy.
That's why I asked folk to reconsider the photo by James yu of the 2 girls in the concrete recess, as really being the work of someone else, things change. Imagine authorship by a known street photographer, where it fitted into a series. That new information would immediately cause a stir, create an enigma, have new attention as both the meaning and value of that "obviously" insignificant image would have to be re-considered!
Asher