I’m also confused. Which songs are you talking about? The first song about Paris that comes to my mind doesn’t feature horns, at least not in the renditions I’ve heard – I’m talking about that old standard about “loving Paris in the springtime” and in the Fall. (Was that Porter? Gershwin?)
Ludovic, do you have any examples? Are you talking about songs in the Tin Pan Alley/Broadway musical tradition? Most popular songs of this type don’t specify orchestrations or arrangements, and many of them have been performed and recorded dozens of times in different ways.
Now I have an image of Priam in Joe Kennedy Sr.'s round glasses, with Joe Jr. insisting “back off, baby brother. I wanna taste of that sugar if I gotta get dragged around over this mess.”
Songs about Paris always remind me of L’ Anarchie Pour le UK from The Great Rock And Roll Swindle, which uses an accordion. So I often associate accordions with songs about Paris.