Restricting played sims from showing up on lots outside their world?

Well, all I can say is I got concerned when the couple from Strangerville showed up at the eatery my Sims were at. I liked it less when the Mermaids would show up at random. I don't believe I've seen too many from the Jungle, but then again I rarely send my Sims there, too. I'm not too sure I'd like it all regimented, though. I do appreciate what you're saying but it's not for me, I think. If there comes a time when this is patched, I do hope there is a toggle.