It’s not London. It’s Harry Potter London. Hence the John Williams score you hear in the background throughout. You will never see anything non Potter related in USF’s London area for this reason. The locations were chosen from the stories, the Knight Bus is parked out front, Kreacher is in the window, if you dial M in the phone booth you’ll get a recording from the Ministry of Magic, etc.
Now a new land can start next door, replacing the now somewhat pathetic World Expo, which only contains one ride. (But don’t expect a second London to show up next to that London lol.) And whatever does show up one day will have a clear delineation between it and Potter London next door.