The point I was raising was regarding the different species of cockroaches. In rural areas there are species that primarily live outside but can find their way inside. German cockroaches tends to be more urban and indoors, so if you see one you can't hand wave it away as having just having hitched a ride into your house.
Being in a city has nothing to do with it. Cockroaches are social, like sheep (or humans). If you live in a city and you find a spider, it was just the one spider. If you live in the remote wilderness and you find a cockroach, it was hundreds of cockroaches.