Why are they called "worlds", and not "towns"?

They'll never be "worlds" in my mind, they are just towns.
The tiny "world" size in this game is what kept me playing Sims3 for a very long time. But one thing Sims 4 always had in it's favour is the travelling ability between towns, eventually after parting with a considerable sum you end up with a huge "world". In my head they're all interconnected and collectively make up a decent area.
But they are not worlds.