Why not lobby for city walls around every settlement larger than ten (or the older "round" unit of 12) houses - then man the towers with cannon toting morons ? That would solve it all surely. The US must be contemplating hard borders between states to fence in each "native" bigot, racist, terrorist, etc. who all have notoriously easy access to a shocking selection of firearms.
The problem is there are just so many foreigners and you never know if it is safe to let one of them in. Only on Thursday I saw an excellent introduction to the clarity in the UK's thinking when I entered the country and the first official sign I saw said "Non-EU passports this way (arrow)". The clarity was instantly muddled up by a woman directing some of the non-EU (namely other EEA) citizens the wrong way (according to the sign). When I pointed out the contradiction, she angrily basically insisted that the EEA is in the EU. If the walls were built then (in the UK) there would most likely be a person posted outside each of them directing people to an unmanned opening or tunnel to the settlement's centre.