But you don't really live in a country without borders. Within the EU doesn't count. In a case of genuine open borders criminals can leave the state quickly to

But you don't really live in a country without borders. Within the EU doesn't count. In a case of genuine open borders criminals can leave the state quickly to avoid punishment. Then move on to a new target country. This doesn't happen only because no country signs an open border agreement without also setting up a legal framework to punish criminals who would try to exploit borders to escape punishment. The reality is that there are bad actors out there and if you aren't stopping them at borders then you'll have to start watching out for them closer to home. High trust nations are like unpatched machines. You need a firewall.