Why would a tourist be detained arbitrarily? Are you referring to that one girl from Berlin? It's ironic to see you talking about statistics of gun violence but suggesting that the statistics of being detained as a tourist are high m.
3,000 out of 66,500,000 visitors per year means you have a 0.004% chance of having this happen to you. You have significantly more chances of dying on your way to work in whatever country you are at.