>Why exactly do you need one? This is one of primary functions of any (democratic) government - to protect its people. People don't want anyone to be able to

>Why exactly do you need one? This is one of primary functions of any (democratic) government - to protect its people. People don't want anyone to be able to come and settle as their neighbour - for both rational and irrational reasons. And governments must listen to their people, because if they don't (like in case of EU/mainly Germany during last migrant crisis) people start having feelings that the government doesn't care about them, which in turn creates room for extreme populist and extremist parties.