In later books, we learn that Jonas does make it to Elsewhere and it is just a fairly normal and somewhat technologically backwards place.  Surely the people of Elsewhere would have not been able to contend with people who had the technology to control the weather and impose sameness.  

Elsewhere can be symbolic, representing death or Heaven.  In this case, Elsewhere would exist as some kind of afterlife.

If you believe that Jonas and Gabe actually made it to another real place that is not another community, then that does raise some questions.  It is possible that other countries take an isolationist view and do not attempt to interfere with the community. 

There are plenty of insular countries in our world with totalitarian regimes that seem to prevent their people from learning the truth about the rest of the world.  We don't intervene. 

It makes sense that the rest of the world would not interfere with the community either.  It also might seem like a utopia, with the killing of people who don't fit in not being well known.  I imagine the community might have a pretty good propaganda department.